The registry number of the USS Enterprise-A in Star Trek V: The Final Frontier is NCC-1701-A.
The Enterprise-A is the replacement for the original USS Enterprise, which was destroyed in Star Trek III: The Search for Spock. It is a Constitution-class refit vessel commanded by James T. Kirk and crewed by familiar officers including Spock, McCoy, Scotty, Chekov, and Sulu.
The suffix “A” indicates the second starship in the Enterprise lineage to carry the basic registry number NCC-1701. The ship had first appeared at the end of Star Trek IV: The Voyage Home, when Starfleet assigns it to Kirk’s crew.
The registry can be confused with NCC-1701, the original Enterprise, or NCC-1701-B, introduced in Star Trek: Generations. NCC-2000 belongs to the USS Excelsior, commanded by Captain Sulu in Star Trek VI.