A virtual switch, or any virtual device supported in smartthings, is just a software proxy that the system will treat like it’s a real physical device, even though it doesn’t exist in the real world. You set it via routines or other automations.
There are many many variations of these: virtual thermostats, virtual dimmers, virtual momentary relays, virtual presence sensors, virtual switches. Right now most of them are available through communitycreated edge drivers.
In the case of a multi endpoint device, where the smartthings app is only showing you the parent device on a tile and making you go into details to see the individual components, the usual workaround is to create a virtual device that can act as a proxy for one of the individual components. Then you use routines so that when the physical component turns on, the virtual device turns on. And vice versa. We say they “mirror” each other, or in the new architecture, they “sync“ to each other.
And that gives you a tile for the virtual device which you can use just like a main tile for the component device. You can name it, control it, use it in routines, even move it to a different room than the parent device.
Here’s the community FAQ on the current options,
FAQ: Creating Virtual Devices with the new architecture (Without the IDE) (2023)
Virtual devices also have many other uses, as you’ll see when you start reading through some of the threads about the edge Drivers.