We use our faces to display our emotions and our personalities, so a face in a dream is often a representation of an emotion or of an aspect of your personality.
You dreaming mind could be telling you that you have been repressing strong emotions and you must learn how to face them and deal with them so they do not overwhelm you, or that you should accept a part of your personality that with which you are unfamiliar or uncomfortable.
If a face in a dream, particularly a disembodied face,seems especially beautiful or especially ugly, this can emphasize how you feel about a quality that you possess or about an emotion that you are experiencing.
A beautiful face can represent a feeling of joy or contentment, or a positive aspect of yourself that you need to develop further.
An ugly face can symbolize an emotion that makes you feel uncomfortable, or a quality that you possess that you do not like.
Dreaming about a face can mean that you are thinking about how you present yourself to the outside world, and how other people see you.
If you dream that you are looking at the face of someone you know, you could be trying to learn more about them.
A dream that someone is hiding their face is a sign that you do not feel ready to learn more about an aspect of yourself.