This is an official term used in baseball to describe a situation where a pitcher earns neither a win nor a loss after pitching in a game. This can occur if the pitcher does not pitch enough innings or pitch long enough in the game to earn the win or the loss. In order to be awarded a win or a loss, a starting pitcher must pitch a full five innings. If the pitcher gets injured, or does not pitch well and comes out early, they will receive a "no decision." Although rare, it is possible for a relief pitcher to receive a no decision if they are not credited with the win, loss, or save.
It is rare for starting pitchers not to pitch long enough to record a win or a loss. If a relief pitcher came in before the sixth inning and then pitched less than five full innings, the relief pitcher could receive a no decision. Since this is an official baseball term, it is tracked in Major League statistics. An example of its usage would be, "Joe Pitcher recorded a no-decision in the game today."