Passed balls are a statistic for when a catcher is unable to stop a pitch that is ruled as catchable (i.e. not a wild pitch), resulting in a runner advancing to another base.
More about Team Passed Balls
In the case of a Passed Ball (PB), the judgment is based on the assumption that the catcher should have been able to catch and maintain control of the pitch that was thrown. In the case of an uncaught third strike, in which the batter reaches first base safely, a catcher can also be charged with a passed ball.