Questions & Answers about Мой друг ездит на север зимой.
Russian has different verbs for going / traveling, depending on how and how often:
- ехать (едет) – to go by vehicle, one time, in one direction
- Мой друг едет на север. = My friend is going north (now / this time).
- ездить (ездит) – to go by vehicle, habitually or repeatedly, or in general
- Мой друг ездит на север зимой. = My friend goes (regularly) to the north in winter.
- ходить (ходит) – to go on foot, habitually or repeatedly.
In this sentence, the meaning is regular, repeated trips by some sort of transport, so ездит is the natural choice.
With cardinal directions (north, south, east, west), Russian normally uses на when talking about movement towards that direction:
- ехать на север – to go north
- лететь на юг – to fly south
- повернуть на восток – to turn east
В север is not used for this meaning. Think of на here as “to(wards)” rather than “on”.