Combos
Combos are the different ways a hand can be dealt, counted to compare how likely holdings are.
There are 1,326 two-card combinations. A pocket pair has 6, a suited hand 4 and an offsuit hand 12. Ace-king therefore has 16 combos and a pair of aces only 6.
Cards you can see remove combos. With an ace on the board there are 3 combos of pocket aces left, and 12 of ace-king.
Related terms
Practise decisions like this in the trainer: ten hands at a time, with the answer and the reason.