Idk what a karen is

It's supposed to refer to a generic woman who is very rude and unlikeable and there's a meme that she hates the manager and keeps complaining, but a lot of kids use it thinking it's funny even though it's really not

Ok thx and its only women?

Karen
Middle aged woman, typically blonde, makes solutions to others' problems an inconvenience to her although she isn't even remotely affected.
Karen sues the local city council after they installed a new STOP sign that hides the sun from her window for two minutes a day. The sign was installed after a school boy on his bicycle was hit by a speeding driver and died.

Karen refuses to wear a face mask for her 5 minute trip to the supermarket during a pandemic. She harasses the workers, asks to see the manager and threatens to sue.

Karen complains that her favorite parking spot was replaced by a ramp for wheel chairs. She parks her car in the old spot anyway and shoots a vlog about it.

From urban dictionary

wow how evil karen is