In baseball, the count refers to the number of balls and strikes a batsman currently has. It is usually announced as a pair of numbers, for instance "3-0", with the first number being the number of balls and the second being the number of strikes. A 3-2 count--that is, one with the maximum number of balls and strikes in a given at-bat--is referred to as a "full count".
An important part of baseball statistics is measuring which counts are most likely to produce favorable outcomes for the pitcher or the hitter.