To build muscle you need to lift a heavy enough weight to fatigue the muscle after 8 to 12 repetitions. Lifting an overly light weight will not build muscle, no matter how many times you lift it. With the right exercise, you can get rid of trouble spots. Spot-reducing is a myth. Exercising one area will not cause fat to be removed from that area.
Men tend to store fat in their abdomens, women store fat more around the hips.
Abdominal and hip exercises can strengthen and tone muscle. But those muscles are underneath subcutaneous layer of fat. Only losing weight can reduce the size of that fat layer. Exercise burns lots of calories. Many people get discouraged at their slow rate of weight loss and quit exercising.