Also known as poker hand combo, it’s a combination of cards that a player can make with their hand. Combos can be suited - AKs or offsuit - KQo. 
In Texas Hold'em, a player's combo is made up of their two hole cards and the five community cards, e.g. AA, AdKc, KhXh. 

There are 6 possible combos of every pocket pair, 4 combos of every suited hand, 12 combinations of offsuit unpaired hands and 16 of any unpaired hand.

Combos also describe a range of hands that a player could be holding in certain situations. For example, a player's pre flop range might consist of a combination of strong pocket pairs, suited connectors, and high suited cards.