What meta is, and how it works is all explained in the Help Center.
This site is the meta site of Arqade. It has its own separate questions, but your rep here is your rep on Arqade. You do not gain or lose rep for votes here. From the Help Center article:
Votes on meta do not affect your reputation; your meta reputation is the same as your reputation on Arqade (synchronized hourly), though you earn separate badges. You must have 5 reputation to participate on meta.
With regards to Meta Stack Overflow, that situation is changing soon, with Meta Stack Overflow to become as this site is to Arqade, and a new Meta Stack Exchange created for questions relating to the Stack Exchange network as a whole.