OOP (Object-Oriented Programming) is just a way to organize (Lua) code. Mostly used when working with a lot of entities/objects = things.
But this option is not for enabling OOP in Lua, it is for enabling OOP in MTA (user-data).
When enabled a lot of methods will available on the user-data of players, vehicles, peds etc.
element:setPosition(x, y, z) -- MTA OOP
setElementPosition(element, x, y, z) -- non MTA OOP
Those methods are also available as functions, so basically it is an enhancement but not required in most cases.
That is irrelevant, but feel free to count.