This stands for English Subtitles , which are often hardcoded or embedded into the MKV file for international viewers.
It is not possible to write a traditional "long article" about the specific filename Climax.2024.720p.WEB-DL.x264.ESub.mkv as if it were a distinct, major cinematic release. Climax.2024.720p.WEB-DL.x264.ESub.mkv