The "bleeding edge" is a term used to describe brand new software that's not guaranteed to be stable. It remains largely untested, but comprises all the latest features that will be deployed to the masses after further experimenting. Kali Linux, by virtue of being based on Debian's testing branch, already sits pretty close to the edge.
This is a companion discussion topic for the original entry at https://linuxconfig.org/adding-bleeding-edge-repo-to-kali-linux