。
Hokkaido is north of Honshu.
Literal
Hokkaido [topic-は] Honshu [of-の] north [in-に] exists.
Geographical positioning with 北 ('north') as a directional noun. の北 ('[X]'s north / north of [X]') — standard way to express 'north of.' にある ('to exist at') uses に for location. 本州 ('Honshu') is the main island of Japan.