Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bc4/3...Bc5/4. Bxf7/4...Kxf7/5. Nxe5

Nxe5+
This move sacrifices another piece, but White will soon get it back with d4 or Qh5+. He will have got a second pawn for the piece, but he would lost the bishop pair and his own king is not out of the center. Therefore, the compensation is not nearly enough and black is close to winning. Do not sacrifice unless you see reason. Here, white didn't have enough development to attack the king successfully.