White brought the queen out on the second move. Because the queen is valuable, it has to run away whenever the opponent's minor pieces attack it, and White loses time.
First look at the threat: the queen attacks the e5 pawn. As Black, defend the pawn by developing a piece: bring the knight to c6.
Now White threatens mate with Qxf7! The best way to defend f7 is to chase the queen with g6.
See: Black developed a piece every move while White wasted time with the queen. Usually bring the queen into play after the minor pieces are developed.