This Lua/Love code moves a square across the screen and when the left side exceed the window width, the square reappears in the upper left of the window.

main.lua

-- 1. in the draw function, update the code to set the rectangle to fill mode instead of line mode (***)
-- 2. in the draw function, update the code to centre the rectangle, in the game window (***)
-- 3. in the update function, update the code to make the rectangle move when you press the arrow keys

function love.load()
  window_width, window_height = love.window.getMode()

  rectOne = {}
  rectOne.width = 200
  rectOne.height = 150
  rectOne.x = window_width /2 - rectOne.width / 2
  rectOne.y = window_height /2 - rectOne.height / 2
  rectOne.move_by_x = 300
  rectOne.move_by_y = 200
end

function love.update(dt)
  -- if 5 < 9 then
    rectOne.x = rectOne.x + rectOne.move_by_x * dt
    rectOne.y = rectOne.y + rectOne.move_by_y * dt
  -- end

  -- if rectOne.x (left side of rectangle) is greater than screen width, set right side of rectOne equal to ZERO
  if rectOne.x > window_width then
    rectOne.x = -rectOne.width
    rectOne.y = -rectOne.height
  end
end

function love.draw()
  love.graphics.rectangle("fill", rectOne.x, rectOne.y, rectOne.width, rectOne.height)
end