"It lets you configure your system in case you have various monitors connected to your PC."
The default Windows screen configuration options are usually insufficient when you have more than one monitor connected to your PC. When this happens, it´s best to have a program like Display Fusion.
Display Fusion configures all the monitors connected to your PC with total precision and detail. For example, you can scale your wallpapers to adapt them to different sized monitors, have a different image on each screen, have a shortcut to the Flickr service to download the images you want, etc.