What is the Gospel Library application, how does it work?

According to the introduction of The Church of Jesus Christ of Latter-day Saints, Gospel Library is a Books & Reference app on the Android platform. There is currently a 5.4.2 (54606.55) version released on Feb 28, 2020, you can see the details below.

Gospel Library is the gospel study app of The Church of Jesus Christ of Latter-day Saints. The library includes the scriptures, general conference addresses, music, learning and teaching manuals, Church magazines, videos, audio recordings, gospel art, and more. Study, search, mark, and share this vast collection.