The Caretaker's Array is a space station built by the entity known only as the Caretaker. It was built in order to allow the Caretaker to bring ships from all over the galaxy (we are only aware of Alpha Quadrant captures) in order to try to extend his life and find a way to keep his species from dying out. The array also sent energy to the Ocampa planet in order to power the systems in the Ocampa habitat under the surface.
Before it was destroyed, the array was damaged in the battle with the Kazon, and Chakotay's ship crashed into it, possibly rendering it unable to send the Voyager home. Voyager's crew were not able to determine how to operate the systems on the station, and with the death of the Caretaker, using it would have been much more difficult. It should be noted, however, that the condition of the station was never referenced as a reason for destroying it.