I think it’s called paracord, strong useful rope, and that is a cobra knot, which is a useful way to carry relatively a lot of rope in a small aesthetic package (but it’s a pain to undo/redo).

Practically useless for evey day use. I doubt anyone who ever bought one of those cobra knotted paracord in bracelets or keychain has ever used the rope in an emergency.

that being said, it’s the insecure male version of a friendship bracelet.