New York is the new York since York is a city in England, but where is Zealand?
The Netherlands.
https://en.wikipedia.org/wiki/Zeeland
It was thus named because it was discovered by Abel Tasman, who was Dutch.
In the Netherlands, bordering Belgium.
It is spelled Zeeland in Dutch.
Zealand is an anglicised name for Zeeland which is province in the Netherlands and used to be one of United Provinces which is also known as the Dutch republic.
Nieuw Zeeland was discovered and named by Abel Tasman in 1642 (who initially named it Staten Landt). The name got later 'adjusted' to New Zealand by Captain James Cook.
Tasman actually called it "Nova Zeelandia" as seen on his old charts: http://www.teara.govt.nz/en/map/10759/map-of-nova-zeelandia
Nova (plural of novum) is Latin for new, the Latinised name changed to the dutch spelling Nieuw Zeeland (which is how we still write it).
Thank you for your answers! Keep rocking!