"The friend is on their right side."

Translation: 朋友在他们的右边。

[JoshuaCros179462]

I am confused as to why 他们的朋友在右边 would be wrong.

[deactivated user]

You are saying their friend is on the right... On the right of what?

[Keith_APP]

That would mean Their friend is on the right side (or plural).

[incazelo]

Your sentences would be translated as: Their friends is on the right side.
'Their' in the question (The friend is on their right side) is refer to 'right side', not 'friends'. So it would be 朋友在他们的右边

[Grunkles]

That sentence means their friend is on their side. It shouldn't specify who's friend it is.

[TiangangLi1]

You're saying 'Their friend is on the right', the sentence is essentially saying 'The friend is on the right in relation to them' (i.e. On their right)