A VGA connector is a type of computer plug. It is used to send analog video signal to an output device like a television screen or a computer monitor. Most VGA connectors have 15 pins; 3 rows of 5 pins. Some of them are a bit different, and have 18 pins; 3 rows of 6 pins.
21st century equipment more often uses digital plugs, mainly by High-Definition Multimedia Interface.