Americans don't use electric kettles - or at least it's very rare. This is unlike Europe, where electric kettles are standard for boiling water. An electric kettle, typically made of plastic or steel, has a heating element on the bottom. The kettle is plugged into an electrical outlet, which powers the coil and heats up the water.
Americans mostly use stove-top kettles. The kettle is filled with water and then heated on a gas or electric stove. The water boils, producing steam, which then flows out of the kettle spout producing a whistle. The whistle signals that your water is ready and you should turn off the stove.