EDIT: Sorry, Coner beat me to the post. I started typing this up like an hour ago before you had a reply, then I got sidetracked for awhile. It's worth clarifying on Coner's reply that VPIP is not every hand played, since AFAIK checked BB's aren't counted even though they're played to the flop. Also he's correct that 20/22 shouldn't be possible, which I didn't even catch.
Typically you see numbers like 20/22/1.8 it refers to VP$IP%/PFR%/AF. Those are the basic stats used to get a feel for someones' play.
These and the myriad other poker stats, and how they are calculated, are defined all over the web on sites and forums like this, and in tracker software documentation. Here's what those three mean in a nutshell:
VP$IP or just VPIP, refers to the percentage of hands where money was voluntarily put into the pot (blinds not included). The interpretations vary among players and their chosen strategies. Generally speaking, I consider above 30 as pretty loose, below 15 or so as very tight, approaching nitty. I'd say most conventional players generally want to be around 20 give or take, but some less conventional strategies or certain table conditions (lots of weak players, a hot run, etc.) might cause a good player's VPIP to run higher or lower than usual, particularly for a given session.
PFR is pre-flop raise percentage, i.e. what percent of hands the player raises pre-flop. Again, open to interpretation but much below 10 usually indicates a more passive or weak pre-flop playing style.
AF is aggression factor, a number which indicates the player's overall tendency to raise/re-raise. I think most consider 1.5 to be a minimum value for this, otherwise you're going to appear very weak and wind up getting run over a lot.
Last edited by Veteran68; 07-09-2008 at 03:05 PM.