Alma 12:10

and therefore he that will harden his heart, the same receiveth the lesser portion of the word; and he that will not harden his heart, to him is given the greater portion of the word, until it is given unto him to know the mysteries of God, until they know them in full;

People who close their hearts get less of God’s word. People who don’t close their hearts get more of his word. They can keep learning God’s secrets until they know them fully.

If someone hardens their heart, they get only a small portion of God’s word. But if someone refuses to harden their heart, they get more and more until they come to know the mysteries of God completely.