The heart is made up of 4 chambers, divided between top and bottom. The left chamber receives blood and the right chamber sends blood out to the lungs. It’s the motor that is used to move blood throughout your body. Arteries carry blood, and distribute that blood throughout the body. Thus, the heart plays the key role in being able to facilitate the transport of this blood.
Blood collects in the top chambers; and begins in the right atrium. It flows from the left to the right (left ventricle to aorta/aortic valve). Valves open and close in order to allow blood in and out of the various atria of the heart.
Electrical signals are what push the heart’s muscles to move. Without the electrical signals, the heart’s muscles would simply go limp and the heart would be a big ball of goo. There would be no activity at all, and the heart would have to be electrocuted to bring it back to life.