I am a beginner in chess. I am playing a puzzle on chess.com and the puzzle is like this:
White to move
[FEN "r4rk1/p4p2/1p2p2p/2p1P3/3p1q1n/1P1PR1N1/P3QP2/R4K2 w - - 0 2"] 1. Re4
Why is this the best move? Is it purely because this is the only way to save the rook, or this move can even gain some pieces?
Thank you in advance!