ABFs are Adult Bible Fellowships and the name describes well what they are all about:
Bible - In order for us to have a growing relationship with God, we believe people have to grow in their knowledge of who God is, what He thinks, how He acts, what He says and that comes through a deeper and firmer knowledge of the Bible.
Fellowship - knowing the Bible is not enough for people to grow the way God intends. To grow like that, one needs to develop deep relationships with other believers and join together in this pursuit of God. The ABFs are the best place to discover and work on those relationships.