This hymn is taken from the Psalm 8, it is verse 2. The background image depicts Pope St. Leo the Great meeting with Attila the Hun. The Latin lyrics and English translation follow:
Domine, Dominus noster, quam admirabile est nomen tuum in universa terra!
Quoniam elevata est magnificentia tua super cælos.
O Lord, our Lord, how admirable is your name in the whole earth!
For your magnificence is elevated above the heavens.