This specific naming convention is a "scene" standard used to identify the quality and source of the file: The title and theatrical release year. 1080p: The resolution (High Definition, 1920x1080 pixels).
Searching for the exact file string typically leads to subtitle repositories and media databases. If you are looking to find, sync, or understand this specific release, Release Technical Breakdown subtitle Black.Widow.2021.1080p.BR.x264.AAC.6ch...
Since this is a Blu-ray rip, subtitles for other "BRRip" or "BluRay" releases of Black Widow will generally sync perfectly. You can find the specific .srt or .ass files on these major platforms: This specific naming convention is a "scene" standard