What is the Spotify Enhance button?

What does the Enhance button do to a Spotify playlist? How can I use the Enhance button on Spotify?

Spotify enhance button

The Enhance button automatically suggests additional songs to match an existing playlist. It does not modify your playlist without approval.

Tapping enhance analyzes the songs in a playlist and places track suggestions throughout the list. These tracks are marked with a green symbol and two action buttons. Select plus (+) to add a song permanently. Choose minus (-) to remove a suggestion.

At any time, tap the Enhanced button to remove any remaining track suggestions.