1.If you are wearing the mask, this is a warning not to reveal too much of yourself in a specific situation. Look to other symbols in the dream to discern what sort of situation this is.
If someone you know is wearing the mask, that person is keeping something from you.
If the wearer of the mask is a stranger, and male, then there is intellectual knowledge out there that you don’t have but should be aware of.
If the stranger is female, you’re not in touch with your emotions and should be.