A galleon was a type of an old Earth sailing ship.
When the Leonardo da Vinci hologram was stolen from USS Voyager in 2374, among other items which included The Doctor's mobile emitter, da Vinci was found on a nearby planet. He told Kathryn Janeway (whom he called "Caterina") that he didn't know how he had arrived on the planet (he believed he was in the New World), but he surmised that he had been kidnapped by Spanish sailors who took him there on a galleon. (VOY: "Concerning Flight")