Complex sentence: The USS "Enterprise" (NCC-1701-B) (or "Enterprise"-B) is a fictional "Excelsior"-class Starfleet starship that appears under the command of Captain John Harriman in the film "Star Trek Generations".
Split into simpler sentences: The USS "Enterprise" (NCC-1701-B) (or "Enterprise"-B) is a fictional starship in the "Star Trek" science fiction franchise. It is an "Excelsior"-class Starfleet vessel that appears under the command of Captain John Harriman in the film "Star Trek Generations".