A ship is a large vessel that floats on water. They serve a lot of purposes - they can fish, serve in warfare, be around just for the helluva it, etc. But te better watch out if te have a ship, because it might be commandeered da Jack Sparrow.
Or, ship is a fictional couple that a fan wants to get together, o is together. It's just a pairing that they love. Ship could also be used as a verb, though. Like: I ship Huddy!
Ship means two things. First. it's what r-pattz said. And if you're talking about TV o movies, it's a couple o a character that te prefer. Like if I say I ship Damon and Elena in The Vampire Diaries, o Ron and Hermione in Harry Potter, this means I like Damon and Elena and Ron and Hermione. If I say I ship Katherine Pierce o Hermione Granger. It means Katherine Pierce and Hermioen Granger are my preferito characters. Hope I helped.