She's not a boxer. Ronda Rousey prior to this entertainment career (next stop is WWE if I'm not mistaken) was olympic medalist in judo. I'm not even entirely sure is this her real persona or an act. Seems that many people prefer her "mean bitch who breaks arms" attitude. That tells a lot about people who follow this crap.
Only reason why I and most other people ever heard of her is her unbeaten record, which has come to an end.