Coyote Time is a mechanic that allows the player to perform an action that can typically only be performed grounded, such as a Jump or Dash, for a few frames after the player character has fallen off of a ledge or platform. Coyote Time is often not noticed by players, but it makes platforming feel more forgiving and decreases the chance an input feels unregistered.
Coyote Time specifically applies to actions which can not normally be executed in the air, and is not to be mistaken for a player performing a Jump or Dash while airborne (a Double Jump or an Air Dash).