The hope is that Enhance will make it easier for you to create new playlists, whether you’re looking to expand your musical horizons or capture a specific mood. It’s a purely optional feature, though, so if you aren’t interested you can always turn it off (or never turn it on).
If you do turn Enhance on, Spotify will provide its own recommendations based on the track list you're listening to. You'll get a new suggestion after every two songs, for a total of up to 30 in a given list. If you like one of Spotify's suggestions you can permanently add it to the playlist with a tap. Spotify points out that this function simply adds new tracks to the list—it won't replace any of the music you have lined up.