Learn German: Wir sitzen hinten. - We are sitting at the back.

Yes! While hin usually shows movement away from the speaker, its root shows up in location words like hinten (at the back) and hinter (behind) to indicate that something is located further away from the front.

Since this lesson is about direction, does hinten mean we are moving to the back?

No, hinten describes a fixed location answering the question 'where?', not a movement answering 'to where?'. If you wanted to say 'We are going to the back', you would use the phrase nach hinten. Because we are using the stationary verb sitzen (to sit), we just use hinten.

What is the difference between hinten and hinter?

hinten is an adverb that stands completely on its own to mean 'at the back', just like in this sentence. hinter is a preposition meaning 'behind' and it always needs a noun right after it, such as hinter dem Auto (behind the car).

Why is the English translation 'We are sitting' instead of 'We sit'?

German only has one present tense. Wir sitzen translates to both 'We sit' (a general habit) and 'We are sitting' (happening right now). English uses 'are sitting' to describe an ongoing action, which is usually the most natural meaning here.