Aerial sockets, also known as TV sockets are wall-mounted outlets for coaxial connectors. They are most commonly used to provide a signal from a satellite (TV aerial) to a TV or FM. A coaxial cable is plugged into a TV and then the other end of the aerial cable is plugged into a socket to connect to the aerial. Aerial sockets often come with a faceplate, also known as wall plate, which screws into the wall. Faceplates come in various materials, such as chrome or plastic, and provide a more aesthetic finish. TV aerial sockets are often found around the home or workplace. You will often find a socket located where TV is to be fitted that requires a satellite signal.
The number of gangs refers to the number of inputs that the wall socket has. For example, if the socket has "2 gangs" you can plug two coaxial cables into it. These cables are available in various lengths and feature a co-ax connector at each end.
Aerial sockets are used when you have outdoor aerials that you wish to connect to. Aerial wall plates are fixed to the wall and you would connect your cable from your TV to the coaxial connector in the wall socket. These cables are available in various lengths to suit your requirements. Your UHF aerial, for example, would feed into the back of the socket. The wiring from the aerial attaches to the board at the back of the aerial wall plate.