It does turn on power to a signal amplifier.
In the "batwing" style of antenna, the amplifier is in the center part of the antenna. The wall plate switch sends 12 volt
power up the coax to power it.
However, a red light at the wall plate just means power is on, the amp could be bad. The UV light breaks down the plastic of the antenna. Water gets in and corrodes the circuit board.
Hook a TV up to the coax connector, raise the antenna and turn on the amp.
Make sure the tv is in "air" mode and do a channel search.
They work really well, all things considered.