"Marina del Rey" technically means "King's Navy". However the Spanish Navy was never known as "marina", but as "armada". Moreover the term "piratas del rey" is legally and historically inaccurate as well, since what is obviously meant are privateers, who were captains of merchant vessels empowered by any sovereign to seize merchant vessels of a nation at war with that sovereign, but were not officially part of his navy. (Privateers or corsairs were regulated by international law until they were abolished in 1856 by international treaty.) Moreover corsairs were not pirates. Privateering was a legal activity. Pirates, on the other hand, were not authorized by any government, but were criminals liable to hanging if caught.
Apparently the original language was not Spanish, this is a translation into Spanish, presumably from German, that is not very accurate.