There are two sections to the Nokia Device Hub. One shows a list of every device that you have connected to. The other shows a list of nearby devices that are using Wi-Fi or Bluetooth. It is those nearby devices that you are managing with this app.
For example, if your computer is using a Wi-Fi connection, it will show up on the Device Hub under the "Nearby" setting. In "Overview," you can see a list of apps that will allow you to connect your phone with your computer. Under "Apps" you will find a list of app that are available to be downloaded on your PC from the Windows Phone Store. Any device that supports Bluetooth or Wi-Fi can be picked up on by the Nokia Device Hub. You can pin a device to your home screen to quickly see which apps will work with it.
Check out the video below to see the Nokia Device Hub in action.
source: WPXBox via WMPoweruser