It's use is to control a 22khz switch, typically to select different LNBF's. Or the operation of a Universal LNBF. where tone off will select <11.7ghz reception, and tone on will >11.7ghz.
If you had a pair of satellite dishes you could then purchase a 22khz switch. It looks like a standard cable splitter. The output from the switch would go to the receiver. Each satellite dish would go to their own input on the 22khz switch.(there are 2 inputs and 1 output.) Then in your satellite menu you have the option to turn 22khz on. When it is turned on it will access one input on the switch. When off it will access the other input. The switch is labeled accordingly. They can be found very cheaply and are a great way to add more dishes to your receiver.