MySQL database

Good Evening to everyone,
sorry for my bad an maybe stupid question… but i don’t even know why i need to make a database to make my server work?
I’d like to make a basic server that work without any resource and then i want to script my own resources with my friends but every time i try to read a guide it says that i must download some resources and the other ones tell me to download other resources too.
So what resources do i have to download to make my server work?
Thanks for patience