3b (122).mp4 -

This indicates the song is in the key of B Major (or its relative minor, G# Minor). DJs use this code to identify tracks that will blend harmonically without clashing.

This specific file naming convention is common in curated playlists or "music pools" used by professional DJs. 3b (122).mp4

This indicates a tempo of 122 beats per minute , typically associated with house music or mid-tempo dance tracks. This indicates the song is in the key