Likely stands for "Full Size" or refers to a specific framing. 720p: High-definition video resolution (1280×720 pixels).
The source of the video rip was a physical Blu-ray disc. x264: The video codec used for compression. Piggy.2022.German.FS.720p.BluRay.x264.ZD.2k.mp4
Specific tags usually associated with the release group or internal encoding specifications. Likely stands for "Full Size" or refers to