Shell Programming and Scripting

Hello friends, good morning
can someone explain to me if he is so kind of what does this mean?

Code:

for i in 6 7 9 A B Z C N F H G M L D R S T 8
do

  echo "input: " $1

done

It is much easier to look at the result of work this code.

Code:

#!/bin/bash
for i in 6 7 9 A B Z C N F H G M L D R S T 8
do
    echo "input: " $i
done

I have to second nezabudka: Why not just run the command, mayhap after consulting man bash:
On the other hand, I have to admit that it may not be the wisest thing to run code that you don't understand (way more complex than above, of course) on a production system. Not a bad idea to have some playground system up your sleeve to test / debug suspect software.
Or use a web test ground like ideone.com.

thank you !!!!

Rudic!!!