The water tank is empty.
When the water tank is empty, the pump gets dry and this can cause noise coming from your steam iron.
Please check the water level in your iron.
If the water tank is empty, fill it with water. Then press and hold the steam trigger until steam comes out of the soleplate.
If your iron is equipped with a water level magnet: Please check if it got stuck in the water container. If it did, you can release it by carefully shaking the water tank or by tapping the side of the container with your fingers.