Albert Barnes Commentary 2 Samuel 20:14

"And he went through all the tribes of Israel unto Abel, and to Beth-maacah, and all the Berites: and they were gathered together, and went also after him." — 2 Samuel 20:14 (ASV)

Abel - More commonly called Abel-Beth-maachah (2 Samuel 20:15) to distinguish it from other places with the name “Abel” (a grassy plain). It is represented by the modern Abil-el-Kamh, a Christian village on the northwest of Lake Huleh, the ancient Merom. Compare this to “Abel-maim” in 2 Chronicles 16:4, which means “Abel by the water.”

And all the Berites - The meaning of this is completely unknown. Many favor the reading of the Latin Version, connecting it with the phrase that follows: “And all the choice young men mustered and followed him.”