"Discovery" is all of the information pertinent to the case that is in the possession of the prosecution (the "state"). Reciprocal discovery is any information the defense has that is pertinent to the case, and that information is to be forwarded to the prosecution.
There is also supplemental discovery, which is any additional information that comes to light after a file has been established at the prosector's (state attorney) office. Both the prosecution and the defense may come across supplemental discovery. A good example is the name of a witness.
Dealing with discovery is what your attorney will do, and you are entitled to a copy of the discovery.
I agree with the other attorney. Discovery is the evidence that will be used in your case. Your attorney will handle all discoverable matters. Speak to your attorney about what is contained in the discovery submission.
Once a Defendant elects to participate in the Discovery process then they have an obligation under the Florida Rules of Criminal Procedure to provide the State reciprocal discovery (which is any information it intends to introduce at trial). In some instances the Defendant and his Attorney may not elect to participate in discovery and therefore not required to provide reciprocal discovery to the State, in a strategic move (very rare move however). It could also be that the discovery demand on the 3rd co-defendant has not been filed yet or maybe in the clerk's office lost.