Need Help with Lua script

Hello people,
I need a help with Lua script.

I would like to know where I can find commands that the fivereborn servers read.

For example:

*** IsControlPressed**
*** GetPlayerPed**
*** GetResourceMetadata**
*** RegisterNetEvent**
*** AddEventHandler**
*** TriggerServerEvent**
*** IsPedPlayerPed**

These commands, How can I know what each one does and where can I find all the compatible commands for the fivereborn servers like the ones above.

Maybe it’s a little silly question of beginners.
But seriously it would help me and one of my many issues …

Thanks everyone anyway. is your best friend.
Some common functions are partly documented.