This describes the source of the video. It means the content was recorded from a High-Definition Television broadcast rather than a Blu-ray rip (BDRip) or a digital streaming service (WEB-DL). Content Context
Used as a standardized naming convention to help users identify the quality and language of a file before downloading. From S01E04 FRENCH HDTV
This usually refers to the title of the television series. In this context, it likely refers to the sci-fi/horror series From (created by John Griffin), which follows the mystery of a town that traps all those who enter. This describes the source of the video
This indicates that the audio track is dubbed in French, or that the file includes hardcoded French subtitles (though usually, "FRENCH" implies a dubbed version for the Francophone market). From S01E04 FRENCH HDTV