Question about header files

So I'm committing some serious taboo and using chatGPT to help me make a CLI text based game I'm making. One thing that struck me as odd was that it kept wanting me to make header files. I asked about this and it said that it was good practice, and I questioned it because from my understanding this adds another file to compile and can create more overhead than needed especially if it's only used once. Now I haven't gotten to a point where I need to use the header files or source code more than once but I want it to be scalable as I work on it. So the main question is this. is it good to make a lot of header files for the game or should I just stick to source code. Why and why not. P.S. I also have looked into what other people say and official documentation but I can't make heads or tails of it.

https://redd.it/1ofd72j
@r_cpp