Keep You In a Safe Gaming Space
Once you start playing a game in roomscale VR it is easy to move around even if you think you are staying pretty still overall.
The Oculus Quest lets you set up a guardian around you when you start it up each time. You simply draw an outline around where you will play and it remembers the boundaries.
Once you are in a world, you won't see this boundary unless you get too close, then it will layer over top of the world so that you know you are about to leave safety.
This is integral in playing VR in almost any room. You do need to account for your reach, as I learned when I slammed into a countertop, but once you set it up correctly it will keep you and your stuff safe.