What are the functions of the right atrium?

Receives deoxygenated (impure) blood from the body via the superior and posterior vena cava to then pumps it to the right ventricle , where from it is sent to the lungs for purification.

De-oxygenated blood entering the heart through veins (from the tissues of the body) enters the heart through the right atrium before being pumped into the right ventricle.

The right atrium is one of the two atria of the heart, which function as receiving chambers for blood entering the heart.

Right atrium also receives deoxygenated blood from wall of heart itself through coronary sinus.