Most likely, with a default setup, reading left to right in a percentage (%) format: Hands played, Raise Preflop, Went to Showdown, Went to Showdown and Won. Sometimes, the "2nd number" maybe defined as an "Aggressive Factor" instead of the "Raise Preflop %". Most of the time though, you will realize who is the loose goose and who won't call a nickel with the 2nd nuts. Not to persuade you from using a HUD, I believe that they are effective, but don't forget the power of intuition ("the FEEL") and purpose for why your opponent is playing,and obviously why you are playing. Read James Mckenna, and you will always have the HUD, rather your HEAD.
GL--OMG--NH--GG,
1StuLucky1