These’ll pretty much be your go to resources when it comes to coding in Lua with FiveM. I’d also advise learning C# instead if you have extra time.
https://docs.fivem.net/
http://www.dev-c.com/nativedb/
https://runtime.fivem.net/doc/reference.html#_n_CFX
https://paste.ubuntu.com/24355443/ – List of Weapons
https://alexguirre.github.io/animations-list/ – List of Animations
https://www.lua.org/