Making a good strike with your irons is key to success on the course. Too many players come to me struggling with thinned or ground first strikes or just generally lacking power in their iron play.
Creating the correct angles with your wrists in your downswing is how you can add leverage to your swing and build power. This will also allow you to attack the ball from the correct angle creating a solid strike. This is also an important part of pitching and will transfer well into your short game.
This drill to improve your iron play is by Mark Jones at Yas Links Golf Club.