There is a minor addition to what Elliot explained. You can also install lights that indicate which way a switch is thrown and indicate if a block is on or off.
A block is a section of track that is electrically isolated and controlled independently of other tracks. Simple example is a siding. A siding can be electrically isolated from the mainline be removing one center pin. That way the siding can be turned on and off independently thus allowing a train to be parked powered down on the siding while another train is run on the main line. You need to run a power wire to each block.
Traditionally, control panels have a drawing of the layout with the switches mounted on the drawing in such a way that you can quickly visually see what switches you need to throw. This gets tricky if you are new to building layouts and might want to change the layout after using it for a while.
Control panels are somewhat out of fashion with command only operators. Personally I love them. I run command and conventional and the panel is appropriate in that case. There are a lot of past threads about this. Do a forum search on "control panel". Some people have done some beautiful ones.
Bill
