If you’re not familiar with gapless playback and what it can do for your music listening experience, it simply means that there is no time in-between music tracks. So basically, you’re listening to a whole album or playlist as just one long, continuous track. It gives you a different feeling, especially if the album is meant to be listened to continuously and in its correct sequence. This is also perfect for classical music, live recordings, concept albums, etc.
Gapless playback is enabled by default once you update to version 3.30 of the Apple Music for Android app. We’re still waiting for something to be added that will make it at par or even better than other music streaming apps though.