To make known to the sons of men his mighty acts. It is a part of the duty of "saints" (Psalms 145:10) to make known as widely as possible—if possible, to all men—the "mighty acts" and glory of God; primarily, for God's glory; and secondarily, to bring about their conversion to God's service.
And the glorious majesty of his kingdom (comp. Psalms 145:5, Psalms 145:11).