what is alpha and omega?

Top wolf, usually leader of pack, and dominant.
Omega usually a lone wolf that goes into a massive heat that makes alphas lose control

Has to do with omegaverse. Basically male and females fall into one of three categories, Alpha (top/impregnator), Omega (bottom/impregnated), and Beta (normals).

Alpha/Omega form a mated pair but depending on the author the rules and such of the omegaverse can be anything.