Nice move from Nepo, stopping Bxc6.

Gaining space on the queenside.

A positional inaccuracy. 15...a5 was a better option.

After this trade, we eliminate the defender of the c5-square, which will be accessible for our knight after fixing Black’s pawn structure on the queenside.

Creating a favorable structure! Now the knight will travel all the way to c5. After that, a rook can come to b3 creating tremendous pressure on the queenside.