"You see red apples."
Translation:Piros almákat látsz.
"Te" is not vital at all, it can be omitted. Depending on context and emphasis, you may or may not omit it. If I want to emphasize you by saying "It is YOU who sees red apples", I would obviously include it in my sentence:
"TE látsz piros almákat". - You see red apples, (and not somebody else). You are the one!