Heart is the most important organ of the body and it is a muscle!
It  cleans our blood and circulates it throughout the body.
In our body , Blood is carried in blood vessels. These are almost like water pipes but only much much smaller.
Blood vessels are of two kinds : Arteries and Veins.
Impure Blood going to the heart is carried in veins.
Pure Blood going away from the heart is carried in arteries.
A heart beat is when the heart muscle contracts. This means the heart scrunches and becomes smaller. This pushes all the blood inside the heart to go out and into the blood vessels (Arteries). Then heart relaxes and gets bigger. This is when all the dirty blood from veins fills up the heart, only to be cleansed again.

Have a heart to answer these?

Have you ever noticed a wavy blue line showing through your skin? What is it?
It is a blood vessel(vein) carrying impure blood.

How many times does your heart beat in a minute?
Anywhere between 60 to 90 times in a minute.

Where is heart placed in our body?
On the left, just above the chest.