This is a rhetorical question. The obvious, implied answer is, ‘No one can!’
No matter how much we tried and tried and tried to express God’s greatness back to Him, we just never could. It’s a relief to know we don’t have to be able to grasp God’s eternal majesty and magnitude in order to earn His favour. In His enormous love, He just pours His favour out on us, anyway. What an awesome reason to praise Him, and put our faith in Him, and do all we can to joyfully love Him with our lives.