No such thing as dumb question right? Each of your “modules” is what the world usually calls a switch or dimmer, depending on whether it goes on/off or dims between on and off. Switches / dimmers are sold individually or in sets. You’ll probably also need a faceplate (the plastic thing that goes over to hide the wires etc. It is up to you to decide what you want to put in the box; two switches, two dimmers or one of each. Whichever route you decide to go, please turn off the power at your breaker/fuse box before you replace the switches.