BRB (Be Right Back) Graphics serve as a privacy screen when your game loses focus in full screen mode or is minimized in windowed mode. It indicates that you are currently not in a game. While the BRB Graphics are active, the audio is also muted. If you have connected your social media accounts you will see the info appear on the default BRB graphics image. If you delete the default BRB graphics image, then the social media images will also be deleted.
To enable BRB Graphics, open XSplit Gamecaster, click on the Settings Tab, and check the box called "Enable BRB Graphics":
If you have a personal or premium license, you can customize the BRB Graphics by clicking on the gear symbol next to the BRB graphics preview window in the Settings Tab:
This will open the BRB graphics editor where you can add a variety of different type of image file types (png, jpeg, gif, tiff, etc.):