When you spin your partner, instead of naturally letting them finish their spin, you catch them in the back to slow them down. This is called a backstop but technically it’s more of a back catch because your movement’s inertia is never really stopped, instead, it is slowed down into a redirection.
Once in the backstop there are many different moves to play with. The most popular are simply to reestablish a secure partner hold or redirect and spin your partner back to where they came from. Get adventurous and discover all the move options.
After you feel good with the backstop try stopping other body parts including hips, legs, elbows, etc.
Practice with the Spotify playlist and your favorite tunes.