: Often refers to a specific release group or "Big Brother" (if related to the reality show).
The string you provided appears to be a for a pirated copy of a movie or TV show, likely sourced from a third-party file-sharing site. Based on the naming conventions in the string: bb-720p-hd-20-oct-desiremovies-mom-mkv
: Likely the date the file was uploaded or aired (October 20th). : Often refers to a specific release group