The chest exercise fly with dumbbells is a great exercise to target your pectoral muscles. Here's how to do it:

Lie flat on a bench with your feet flat on the ground, holding a dumbbell in each hand. Your palms should be facing each other, and your arms should be extended above your chest with a slight bend at the elbows.

Lower the dumbbells out to the sides of your body in a wide arc, keeping your elbows slightly bent. Lower the weights until your arms are level with your shoulders or until you feel a stretch in your chest muscles.