The name of this game is Pepper.
A coach gathers a small group of players which are only a few feet from him/her.
The coach then hits or bunts the ball to the players in any random order, then the players must use quick reactions to retrieve the ball and accuracy to pitch, this pitch is only a toss, for the coach to hit again.
You do this drill to improve the players reaction time.
You have to do this drill as quickly as possible and the pace will increase as time goes on, and the players improve.
This can also be used to help players with bunting by having a player bunt the ball in place of the coach.