I get those sometimes from shaving. Usually I just pop them and they go away. It's usually what Pcogale said, "Could be an infected hair follicle, especially if you shave. But more that likely it's a cyst." It'll go away.
Could be an infected hair follicle, especially if you shave. But more that likely it's a cyst. These should eventually get reabsorbed by the body but it may take months. Or a doctor can lance it and get the inside out. Get a check up if you are really worried. Better to be safe than sorry.