Learn German: Wohin gehst du? — Nach Hause. - Where are you going?

In English, "where" can mean both a location (where you are) and a direction (where you are going). In German, these are different! Wo asks about a fixed location, while Wohin literally means "where to". Since this sentence is about movement towards a place, we must use Wohin.

Can I split Wohin into two words?

Yes! In spoken German, it is very common to split the word. You will often hear Wo gehst du hin? instead of Wohin gehst du? Both mean exactly the same thing.

Why is "home" translated as Nach Hause? Doesn't nach mean "after"?

Nach can mean "after" (like in time), but it also means "to" when talking about travel to cities, countries, and home. Nach Hause is a fixed phrase that specifically means you are moving towards your home.

Could I say Zu Hause here instead?

No, because zu Hause means "at home" (a fixed location). You use zu Hause to answer Wo (Where are you?), but you must use nach Hause to answer Wohin (Where are you going?).