If the umpire’s count is 2–1, the batter has one strike. In baseball, the first number traditionally represents balls and the second number represents strikes, so 2–1 means two balls and one strike.
The count records every legal pitch during a plate appearance. A batter reaches a full count at three balls and two strikes. Four balls result in a walk, while three strikes result in a strikeout, subject to baseball’s detailed rules about foul balls and whether the third strike is caught.
A foul ball normally adds a strike when the batter has fewer than two strikes. Once the batter has two strikes, an ordinary foul ball does not create a third strike, although a foul bunt with two strikes is an exception. This is why the count is more than a simple running total of swings and misses.
Baseball broadcasters often say the count as “two and one” or “two-one.” Some leagues and eras have displayed or announced the count in a different order, but the standard modern notation used in Major League Baseball puts balls first and strikes second.