I only have about 35 games experience , so please excuse blunders.
I am in the following position. My app (dr wolf) wants me to capture on a3. However I fail to see either the extreme threat posed by the enemy Knight, or the extreme utility of the enemy vacating the b column, that would justify sacrifice (corr.: exchange) of my bishop.
[FEN "r1bqkbnr/ppp2ppp/2n5/4p3/3p4/N1PP1N2/PP1BPPPP/R2QKB1R b KQkq - 0 1"]
Can anyone explain the strengths of this move?