global.lua contains a list of all the available commands with brief description.
The Lua scripting guide (which for some strange reason is only available on the steam pages) is a good first step.
Someone is currently writing a book! (which everyone can buy and then not read)
The Script forum is the best place to hang out for Lua related stuff, there is a whole - very long - thread there full of example scripts.
Then there are the video's, tons of them made by Lee showing off his scripting skills.
Oh and there is this
https://forum.game-guru.com/thread/219215#msg2594062 which is quite handy.
But first I'd suggest learning Lua, buy the official book it's well worth it. GG uses Lua 5.2 btw.
btw, welcome to GG land.
btw2, I am in the process of creating a suite of modules to provide more useful Lua commands, utillib.lua & physlib.lua are already available in script bank. Each new function has a description with it. The idea behind the modules is to provide more powerful and better performing functions for the more common things people need to do in scripts.
Been there, done that, got all the T-Shirts!