It often means hit away if the batter has 2 strikes on him or her. If there are less than 2 strikes on the batter, it means what ever the coach wants it to mean, including it means nothing at all and is only a fake sign.

Hello,

Im sure this information is late in getting to you, but I noticed the two other responses did not deliver the correct information. As a player, and a coach the most common meaning of a coach pounding/tapping two fists together is to indicate that the count to the current batter is a full count as in 3 balls and two strikes. Lots of things happen on a full count depending on how many outs and where the runners are.

This is the most common use of that sign.

No need to be sorry.

You may have seen coaches use it for OTHER things, but the most COMMON usage is to note full count. While I appreciate what other coaches use it for, have an ask around and give the sign to somebody without prompting them i.e. walk up to a baseball guy or gal and do the sign and ask them what it means when a coach or umpire does it in a baseball game. My bet is that you would get an overwhelming response of people saying 'Full count' or 3 and 2... it indeed is the exception that make the rule (not that this is a rule just a COMMON usage of it in Baseball and Softball)

In my playing Career thru High School, College, and in the Minor Leagues we did all kinds of crazy things to confuse the other team, and as a Short Stop we would commonly do things to confuse runners and batters. One of my favorites would be to call out how many outs we had... saying TWO OUTS, but holding up the right number of outs... My teammates knew to read my hands and not my words, but most runners tend to listen to my words, this causing many runners to get caught in a position they did not want to be in because they thought it was two outs when in reality it was no outs or one out...

Signs are a fun part of baseball and some really good coaches are fun to watch when they are giving signs. I think most people would be surprised at how many signs are givine and by who in any game situation during a baseball game. Situations aside I am sure you have seen it used for many different things, but most common usage is to note a full count.