This refers to the cards that are dealt face-up in a poker game, also referred to as community cards. In flop games, like Texas Hold’em or Omaha, five cards are dealt face-up in the center of the table. In Seven Card Stud, four cards are dealt face-up in front of each player.
When playing Texas Hold’em, players are allowed to use any combination of their own cards and the board. This means if the best five-card poker hand a player can make is by using all five community cards, then that is his or her final hand, otherwise known as “playing the board”.
For example, if you have A-2 on a board of 2-3-4-5-6 you would be playing the straight on the board. In these situations the pot would be split if an opponent does not have a 7.