Default and communications devices
It can be confusing when you have only one microphone or speakers connected to your computer, but for some reason more are displayed in the list for selecting devices.
If you look closely, you'll notice that each of these items actually contains name of your device and precedes by "Default" and "Communications" prefixes. These are sort of device roles assigned by your operating system. And they make sense, of course, when you have not one, but several devices.
As you can see, we now have two devices, one of which has the role "Default" and the other "Communications". These roles determine when a particular device is used and can be changed in Windows sound settings.
Microphone and speakers with "Communications" role are used, the name speaks for itself, for communication, phone calls or in applications for online conferences (Zoom, Skype, etc).
For example, this can be useful when you have a microphone with more suitable directivity to call colleagues, or mic is built into a webcam in direction of which you are facing.
Also, it may be more comfortable making phone calls using headphones, and for other sounds you have other better speakers.
These devices will be used for everything else except communication.
For example, a microphone for podcasting or voice recording may not be as convenient for video calls, so you can give it "Default" role.
It is also more pleasant to listen to music on high-quality speakers than in simple headphones, which give some privacy for working communication.
To set desired roles, right-click on Sound icon, which is located in the lower right corner of the screen, and select Open Sound settings.
On the right or bottom of the opened window, find Sound Control Panel and click on it.
All playback devices, that can be used, are listed in the opened window. To set default one, right-click on it and select Set as Default Device.
In the same way, you can assign "Communications" role to another device.
For microphone select Recording tab.
And distribute appropriate roles in the same way as speakers.
Of course, you can only set roles if two or more devices of a certain type are connected.
You can see a list of all your devices and what roles they have when testing a webcam.
If you do not have webcam, microphone test also displays recording and playback devices.