Can girls play college football?

Yes, but it is rare.

Katie Hnida, was the first woman to score in a Division I-A college football game as the kicker for the New Mexico Lobos.

Liz Heaston had previously scored for NAIA Division III Willamette University, and Ashley Martin had previously scored for NCAA Division I-AA Jacksonville State University.

I have never heard of a girl playing any position other than kicker.