Weight Forward means that you will have more of your body's weight on the foot that is closest to the target. For right handed players it is your left foot. The rule of thumb with Weight Forward is that you should start with 60% of your body's weight on your left foot and keep it there throughout the golf swing. Here is the practice drill to help feel the benefits of Weight Forward.

Take your normal address position.  Position 60% of body's weight on your left foot.

Take your normal swing with a 9 iron, keeping your Weight Forward.

Hold your finish.

Repeat this 10 times.

You will soon notice much better contact with the golf ball. Improved contact will lead to more control of distance and accuracy. Proper ball-striking is one of the biggest keys to lowering your score.