When do i use void/string?

[Rex_Ng]

Hi gamedev community. I was attempting the challenge on s02 lesson 24 and was able to run my command without error. However the solution shown was not the same as the solution i utilized. Here is my code.
Here is a screenshot of ben’s code.

. so whats the difference between using void/string?

EDIT: its ok sam mentioned that it will be explained in future lectures later in the video. My bad. Sorry.