Originally Posted by: SFDonovanI saw this in some tabs for a song. 3p1p0

What does it mean? Are these pull off's and how many ways can they be depicted in a guitar tab?

Yes, those are pull-offs. I cover that here:

http://www.guitartricks.com/lesson.php?input=19671&s_id=1540

They can also be indicated by a phrase, or slur mark. This is the curving arc drawn over the notes that are connected by pull-offs or hammer-ons. You can see them in the notation on that lesson page.