What is the real meaning of prayers?

The Qur'an says;

The Criterion, 77.. Ayet: Say (to the Rejecters): "My Lord would not concern Himself with you but for your call on Him: but ye have indeed rejected (Him), and soon will come the inevitable (punishment)!"

The Criterion, 77.. Ayet: Say: My Lord would not care for you were it not for your prayer; but you have indeed rejected (the truth), so that which shall cleave shall come.