“A mask is an article normally worn on the face, typically for protection, concealment, performance or amusement” ( http://en.wikipedia.org/wiki/Mask) . As a metaphor nowadays, masks are pit occasionally by a person to hide it’s real self, which can also be to elate his/her stature in the society. Males putting on the mask of a tough guy is one such example where he thinks his inner feeling cannot be accessed cause of this mask that he is wearing which then gets suppressed down.
Masks can sometimes also be useful, e.g. a person has to go for a job interview, or cheering for your friend even he’s playing well are good examples.
Masks in a person's life is inevitable, and are neither wrong to have, it just depends to the way the masks are being used.