This is a blocking drill designed to help a catcher move quickly from side to side as well as react to balls in the dirt.
Place three baseballs on the ground in front of the plate one middle and one on either side of the plate. Have the catcher set up behind the middle baseball and react to the coaches directions.
After a coach points to a ball, the catcher is to move towards that ball in a blocking position.
From his knees, the catcher pops up to his feet and moves back behind the plate to react to the next assignment. Start slowly and increase speed as appropriate, but be careful to maintain proper technique.
Finally, be sure the catcher is back into his blocking/throwing stance before pointing to the next ball.
For more information, check out my book Coaching the Beginning Pitcher.