Das sind ihre Lehrer. Why are there more than one teacher?
So, according to DuoLingo, "Das sind ihre Lehrer.," translates to "Those are her teachers." The only part of this I would think that would make the sentence have more than one teacher is the "ihre." So my question is, is ihre the reason for more than one teacher? Why? And what would be the replacement if there were to be one teacher.
EDIT: I now realize that ihre is plural and ihr is singular. So now does this mean that ihre and ihr control whether the associated noun's is plural or singular?