It's basically marking the other person as theirs (bonding). Different omegaverses have their own additional rules, but I've read some where imprinting has these effects:
-makes it so the omega can only respond to the alpha's pheromones (like calming down)
-ONLY getting pregnant with the alpha who imprinted on them
-can't smell other's pheromones beside's their alpha's
Megumi and Tsugumi is an example where they kinda talk about how imprinting is for life and their parents want them to be absolutely sure of their decision. There's prob a few other ones but when its consensual then it makes everyone happy :)
Instant Family is an instance where they imprinted for life since they were kids
I think in Kiss Me Liar the imprint can only be done if the Omega says okay (so the alpha can't force it)
Into The Rose Garden they're imprinted in one timeline and it follows into the rest of the 2
Y’all help can someone educate me on what imprinting is? I’ve never heard of this in any omegaverse I’ve read before.