In NLH you have to use 5 cards to make a hand at showdown, and these cards can be either your hole cards or the community cards. If your hole cards can not improve on, whats already on the board, you are "playing the board", and the best you can hope for is to chop the pot. In some rare situations the board is the nuts, and it will always be a chopped pot. An example is a board like 6666A. Another example is AKQJT with no more than two cards of the same suit.