Can you please explain the usage of a thermostat for my snake.

I dont really know what everyone means by it, i know a thermostat cotrols temps, but how can you hook one uo to control the cage.

And if i get this will i need my heat lamps anymore or is the thermostat good.

Let me know best you can like how the process of setting it up works, how big it is, and how expensive it is.

Also where can i get one?

sorry for the n00b question, but im looking to change my snakes source of heat.