Where did this file come from (e.g., an email, a website link)? What were you expecting to download? I can then give you a more specific assessment.
.m3u (MP3 URL) is a plain text file that contains a list of paths or URLs to media files, not the actual audio/video content itself. Download File 3 (8).m3u
If you expected this file from a trusted source (e.g., a radio station stream, a known music site), it is generally safe. Where did this file come from (e
It is used by media players (like VLC, iTunes, or Winamp) to play a sequence of media files in order. Risk Assessment: a radio station stream