You use the stats to determine what sort of
hands they play, and how they play in various situations. You're basically putting them on a range of possible hands.
If someone has 50/4/.8 stats (voluntarily puts $ into pot/pre-flop raise/aggression factor) and he limps in ahead of you, your K/T is probably the best hand and you can raise him.
If that same guy raises, be very careful because he's only raising with premium hands.
And if that guy bets the flop, he probably has a pair or better as he's not one to bet with air.
Or if the stats show that a guy 3-bets a lot you can 4-bet
bluff him and take down a good pot.
Or if a guy c-bets a lot you can check/raise him as a bluff.
Those stats are an accurate way to see how he has played, so you can make educated estimates about how he's playing now and exploit it.