It means infinity. For example, a pitcher pitches a batter and that batter hits a home run. ERA is calculated by (winning race / entry * 9). Since the total of the entries is 0 (he took no one), the ERA is INF, infinity.
It happens quite often.
This site can help you.
What does inf mean in fantasy baseball?
If it’s in the category of ERA stats, it means infinite in terms of ERA, which occurs when a pitcher gives up at least one earned run without recording an elimination.
If it’s a position on your team, it means infield, where you can field a player who is at first, second or third base or shortstop.
It means “infinity”, like the average number of points won by a pitcher. If the pitcher comes in and faces a batter who hits a home run, then the pitcher has allowed a run in zero innings pitched. It’s nothing unusual.
I think it’s an inflator. In other words, it warns you that the player you are about to sign is too big. Then move on to the next player. (it’s in the field, really)