ttt.jl

VOID = '_'
HUMAN_SIGN = 'x'
BOT_SIGN = 'o'
DRAW_SIGN = 'N'
BOARD_LENGTH = 3

board = [['_','_','_'],['_','_','_'],['_','_','_']]
bot_board = [[3, 2, 3], [2, 4, 2], [3, 2, 3]]

function start()
    println("·singleplayer - type 1")
    println("·multiplayer - type 2")
    choose_mod = readline()
    if choose_mod == "1"
        players = 1
        println("·Your sign:", HUMAN_SIGN)
        println("·Computer's sign:", BOT_SIGN)
    end
    if choose_mod == "2"
        players = 2
        println("·1st player's sign:", HUMAN_SIGN)
        println("·2nd player's sing:", BOT_SIGN)
    end
    println("·Input Example: B2")

    print_board()
    human_step(players)
end

function input_coord()
    i = 4
    j = 4
    while i > 3 || j > 3 || board[i][j] != VOID
        print("Position:")
        input_str = readline()
        println()
        i = Int(input_str[1]) - Int('A') + 1
        j = Int(input_str[2]) - Int('0')
    end
    return i, j
end

function human2_step()
    i,j = input_coord()
    board[i][j] = BOT_SIGN
    print_board()
    check_game_over(2) #players
    human_step(2) #players
end

function human_step(players)
    i,j = input_coord()
    board[i][j] = HUMAN_SIGN
    print_board()
    check_game_over(players)
    if players == 1
        bot_analize(i, j)
    else
        human2_step()
    end
end
function print_board()
    println("  1 2 3 ")
    for i = 1:BOARD_LENGTH
        print('A' + i - 1,' ')
        for j = 1:BOARD_LENGTH
            print(board[i][j],' ')
        end
        println()
    end
    println("_________")
end

function horizontal(k, char)
    n = 0
    lst = [-1]
    for i = 1 : BOARD_LENGTH
        if board[k][i] == char
            n += 1
        end
        if board[k][i] == VOID
            lst = [k, i]
        end
    end
    return n, lst
end
function vertical(k, char)
    n = 0
    lst = [-1]
    for i = 1:BOARD_LENGTH
        if board[i][k] == char
            n += 1
        end
        if board[i][k] == VOID
            lst = [i, k]
        end
    end
    return n, lst
end

function diagonal(diagonal_type, char)  # 1- from vverhni corner
    n = 0  # 3 - from left down corner
    lst = [-1]
    j = 3

    for i = 1:BOARD_LENGTH
        if diagonal_type == 1
            j = i
        end
        if board[i][j] == char
            n += 1
        end
        if board[i][j] == VOID
            lst = [i, j]
        end
        j -= 1
    end
    return n, lst
end

function check(n, lst,char)
    if n == 2
        return [lst]
    end
    if n == BOARD_LENGTH
        game_over(char,1)
    end
    return []
end

function bot_analize(h_i, h_j)  # human i and human j

    danger_coordinates = []
    maximum_coordinates =[]
    win_checks = []

    # It's first part of analize, checking
    # dangerous checks for bot and win checks
    # for bot
    for i = 1:BOARD_LENGTH
        n, lst = horizontal(i, HUMAN_SIGN)
        append!(danger_coordinates,check(n, lst, HUMAN_SIGN))
        n, lst = vertical(i, HUMAN_SIGN)
        append!(danger_coordinates,check(n, lst, HUMAN_SIGN))
        n, lst = horizontal(i, BOT_SIGN)
        append!(win_checks,check(n, lst, BOT_SIGN))
        n, lst = vertical(i, BOT_SIGN)
        append!(win_checks,check(n, lst, BOT_SIGN))
    end

    for j = 2:BOARD_LENGTH
        n, lst = diagonal(j, HUMAN_SIGN)
        append!(danger_coordinates,check(n, lst, HUMAN_SIGN))
        n, lst = diagonal(j, BOT_SIGN)
        append!(win_checks,check(n, lst, BOT_SIGN))
    end
    #########################################

    bot_board[h_i][h_j] = 0
    for i = 1:BOARD_LENGTH
        if bot_board[h_i][i] != 0
            bot_board[h_i][i] -= 1
        end
        if bot_board[i][h_i] != 0
            bot_board[i][h_i] -= 1
        end
    end
    if h_i + h_j == 3
        j = 3
        for i = 1:BOARD_LENGTH
            bot_board[i][j] -= 1
            j -= 1
        end
    end
    if h_i == h_j
        for i = 1:BOARD_LENGTH
            bot_board[i][i] -= 1
        end
    end
    maximum = 0
    for i = 1:BOARD_LENGTH
        for j = 1:BOARD_LENGTH
            if bot_board[i][j] > maximum
                maximum = bot_board[i][j]
                maximum_coordinates = []
                append!(maximum_coordinates,[[i,j]])
            end
            if bot_board[i][j] == maximum
                append!(maximum_coordinates,[[i,j]])
            end
        end
    end
    x = -1
    y = -1
    if x == -1 && y == -1
        ###############################
        i = rand(1:length(maximum_coordinates))
        while maximum_coordinates[i] == [-1] || maximum_coordinates[i] == []
            i = rand(1:length(maximum_coordinates))
        end
        x = maximum_coordinates[i][1]
        y = maximum_coordinates[i][2]
    end
    if board[2][2] == VOID
        x = 2
        y = 2
    end
    for i = 1:length(danger_coordinates)
        if danger_coordinates[i] != [-1] && danger_coordinates[i] != []
            x = danger_coordinates[i][1]
            y = danger_coordinates[i][2]
        end
    end
    for i = 1:length(win_checks)
        if win_checks[i] != [-1] && win_checks[i] != []
            x = win_checks[i][1]
            y = win_checks[i][2]
            board[x][y] = BOT_SIGN
            print_board()
            game_over(BOT_SIGN,1)
        end
    end
    bot_step(x, y)
end

function bot_step(i, j)
    # x = i, j = y
    board[i][j] = BOT_SIGN
    bot_board[i][j] = 0
    print_board()
    human_step(1)
end

function check_game_over(players)
    if(board[1][1] == board[1][2] == board[1][3] != VOID|| board[1][1] == board[2][1] == board[3][1] != VOID || board[1][1] == board[2][2] == board[3][3] != VOID)
        game_over(board[1][1],players)
    end
    if(board[2][1] == board[2][2] == board[2][3] != VOID ||  board[1][2] == board[2][2] == board[3][2] != VOID)
        game_over(board[2][2],players)
    end
    if(board[3][1] == board[3][2] == board[3][3] != VOID || board[1][3] == board[2][3] == board[3][3] != VOID)
        game_over(board[3][3],players)
    end
    if(board[1][3] == board[2][1] == board[3][1] != VOID)
        game_over(board[1][3],players)
    end
    if !(VOID in board[1]) && !(VOID in board[2]) && !(VOID in board[3])
        game_over(DRAW_SIGN,players)
    end
end

function game_over(char,players)
    if char == HUMAN_SIGN
        println("·1st player win!")
    end
    if char == BOT_SIGN
        if players == 1
            println("·You lose :(")
        elseif players == 2
            println("·2nd player win!")
        end
    end
    if char == DRAW_SIGN
        println("·Draw")
    end
    exit(0)
end

Nice work! There are definitely some efficiency improvements needed but it looks great.