Zeeland (not Zealand) is a province in Holland, a coastal strip bordering Belgium. It contains a number of islands and about half of its area is water - hence the name, meaning sea-land.
How New Zealand got its name: In 1642 the Dutch seafarer Abel Tasman became the first European to discover New Zealand, which he named 'Staten Landt' on his maps, thinking it was an island off Chile sighted in 1616. When it was realized that they were two different places, the Dutch mapmakers gave the archipelago the Latin name 'Nova Zeelandia' after the Dutch province. The Latin became the Dutch 'Nieuw Zeeland', which was in turn misspelled 'New Zealand' by the English explorer Captain James Cook.
Abel Tasman also discovered an island off Australia which he named Van Diemen's Land, but was later given the more appropriate name of Tasmania.