There is a theory that he was killed by the kgb for making anti soviet songs and he made this song as a “call for help” as such or trying to tell people what will happen to him without giving it away too much. Although i don’t know how true it is
this song is about the transience of our life, about the fact that anything can happen to everyone at any moment and you need to be ready for it. I see in this song the message that you need to live as if tomorrow is your "last day"