The app listen to currently playing music and give you a hint, what will be the matching dance for you and your partner.
Maybe you find it more useful on Apple Watch, so no worries, its included.
Keep in mind, maybe it will not always right predicted. The percent info show you the Apps confidence.
App detects:
Disco Fox
Disco Samba
Foxtrot
Rumba
Cha Cha Cha
Waltz
Slow Waltz
Tango
Jive