I'll give you the basics:
There are 3 five minute rounds for non title fights (every main event from now on will be 5 rounds as well regardless if it is a title fight).
5 five minute rounds for title fights
The champs in each division are:
Bantamweight: Dominick Cruz
Featherweight: Jose Aldo
Lightweight: Frankie Edgar
Welterweight: Georges St. Pierre (known as GSP)
Middleweight: Anderson Silva
Light Heavyweight: Jon Jones
Heavyweight: Cain Velasquez
A fight ends either by knockout, referee stoppage, submission, or obviously when the time runs out and it goes to a decision.
The most common stand up technique is muay thai kickboxing(although most fighters pick and choose the best techniques from a few different types of martial arts)
The most common ground techniques are wrestling (Typically Greco-Roman, Freestyle, and/or Catch)and Brazilian Jiu Jitsu. Sambo and Judo practitioners are also fairly common.
Those are pretty much the basics.
Fun fact for a girl to know to impress a guy: Royce Gracie was the first UFC champion.
I mean its somewhat common knowledge among the mma community but if a girl told me that I'd be fairly impressed.
Dumbest thing I've heard a girl say had to be from my ex who asked: "why doesn't he just push him off??"