"Elle s'habille a six heures"
How do I tell the difference?
You can't. I have added it to the list of homophones for audio exercises only. It may take a while for staff to act on it.
I also have the question, how do you tell plural from singular in this situation. They sound very similar?
No, I don't think they sound different here either. The "ent" ending on the plural verb is never pronounced, the reflexive pronoun is "se/s'" is the same and "elles" sounds the same to "elle" when in front of a consonant