Black’s knight on d4 is creating a great deal of trouble; it's about to take White’s queen and also threatens a fork at e2. The natural idea is to take the knight—but with your bishop or with your own knight? Consider what else you can do with either of them. White’s knight is on a light square, and so are Black’s queen and rook (and his king, but for now only the queen and rook are within range). White would like to play the fork Nxe5, but now he can’t. The problem isn’t the pawn on e5; it’s the pawn on f6 that guards e5. White has no other pieces he can use to capture either pawn, but the more natural way to get rid of troublesome pawns is to capture things they protect, for then they move to recapture and no longer guard the squares they once did. So White breaks the logjam with BxN, forcing Black to recapture with e5xB. Now the path is clear for White to play e4-e5, still in an effort to get the f6 pawn to move. Black has to play f6xe5 (if he instead moves his knight away from d6, White pushes the pawn to e6 and forks the rook and queen with cover from his own queen at b3). At last nothing guards e5, so White can play Nxe5, forking queen and rook and winning the exchange.

Observe how the whole sequence was driven by an idea: if the f6 pawn could be lured off of guard duty of e5, the fork would be possible; so White works on ways to attract it away with captures and threats.