It’s a technology by AMD. FidelityFX Super Resolution. Basically, it is a technology that lets you improve the performance of a game while not sacrificing too much quality.
If I remember correctly, the way it works is by running the game at lower than native resolution (say 720p instead of 1080p) and then using fancy algorithms to upscale the graphics back to native resolution. It tries to get the best of both worlds, the better performance of running at a lower resolution and the better graphics of a higher resolution.