: The audio codec. 5.1 means it supports surround sound (center, left, right, two rear speakers, and a subwoofer).

: Downloading files from third-party distribution sites like "HDMovies4u" carries a high risk of malware, adware, or phishing.

: This seems to be the source or the website from which the movie was downloaded. HDMovies4u might be a platform known for providing high-definition movies.

If you were writing a paper, each segment of your file name represents a different layer of digital distribution: