It spawned from western fandom culture
Omegaverse is a world where people are divided into three types: Alpha, Beta, and Omegas. Betas just like average people from our universe. Alphas tend to be more attractive and successful and athletic. Oh, and female alphas can impregnate individuals. Omegas go into heat once a month and an carry child regardless of sex. An omega's pheromones affect those around them typically until they bond with an Alpha. Once bonded an Omega's pheromones will only affect their bonded partner. Betas cannot bond with Omegas.
The exact details vary depending on how the writer of the work wants to write it but that is the broad strokes of it.
did anyone know where this Omegaverse thing come from !? I really like it :P and I'm wondering
At first I though it was just some dj from Shingeki no Kyojin but I now see it more often in various yaoi