Thank you for posting.
Boils are a very common skin infection. Another name for a boil is a furuncle, and when multiple boils occur on the body, the condition is called furunculosis. Several boils joined together with tunnels under the skin are called a carbuncle.
As a boil gets larger a cavity inside forms and fills with pus. This is called an abscess. Once drained, the hole is essentially the area (cavity) where the pus had built up. It should heal over in time. If it does not or becomes infected, see a dermatologist.