script.sh

#!/bin/bash

#Creating the five directory
mkdir ./five

for counter in {1..5}
do
    #Creates the dir1..dir5 directories
    mkdir ./five/dir$counter
    
    for files in {1..4}
    do
        #Creates the files inside de dir1..dir5 dirs
        touch ./five/dir$counter/file$files.txt
        
        #BLACK MAGIC ALERT: using the comand seq to iterate over sequence of number
        #More info on stack overflow: https://stackoverflow.com/questions/169511/how-do-i-iterate-over-a-range-of-numbers-defined-by-variables-in-bash
        for echo in $(seq 1 $files)
        do
            echo "$files" >> ./five/dir$counter/file$files.txt
        done
        
    done
done