This is the release group. In the piracy and encoding scene, groups have reputations. (often standing for "Public Server Announcements" or simply a branding) is famous for aggressive compression.
Here’s a short story based on the release title you provided: Spectre.2015.1080p.10bit.BluRay.8CH.x265.HEVC-PSA
The at the end likely stands for a group or entity that provided the rip, possibly a dedication to the scene or a watermark. This is the release group
This is self-explanatory. It identifies the movie title and the release year to avoid confusion with the 1970s TV series or other films of the same name. Spectre.2015.1080p.10bit.BluRay.8CH.x265.HEVC-PSA