Vespers of our Angel Guardians has a twofold focus: first, as always, praise of God, imitating the chief and eternal duty and joy of His Angels; secondly, respectful veneration of the Angels in gratitude for their ready care for us, as the Lord commands.
"The Lord hath mandated his Angels concerning thee, that they guard thee in all thy ways" (first antiphon); "Blessed be God, Who sent His Angel, and freed His servants who believed in Him" (fourth); "Behold, I will send My Angel, Who shall precede thee and guard thee in the way and bring thee to the place which I have prepared: obey him and listen to his voice" (little chapter); "Holy Angels, our guards, defend us in battle, that we perish not at the tremendous Judgement" (Magnificat antiphon): these sentences sum up our knowledge of and trust in those ministering spirits sent to help us, the heirs of salvation.
In the other antiphons, the primary concern of the angels - the adoration of God Almighty - is confessed, and our lowly praise is joined to theirs (as every Preface sings at Mass): "Let us praise the Lord, Whom the Angels praise, Whom the Cherubim and Seraphim proclaim Holy, holy, holy" (second antiphon); "Their Angels ever behold the Face of My Father, Who is in heaven" (third); "Praise the Lord, all His Angels; praise Him, all His Powers" (fifth); "In the sight of the Angels I will psalm unto Thee, my God - I will worship toward Thy holy temple, and confess Thy Name" (versicle).
The hymn (by St Robert Bellarmine) sums up much of this - here is a translation, perhaps by Neale:
The Guardians of our race, our Angel Guides we hail;
our Father sendeth forth to aid our nature frail
these heavenly friends, lest we should suffer overthrow
through cunning of our subtle foe.
For he, who justly lost the honour once his own,
the traitor angel, rues his lost and vacant throne,
with burning envy strives to make them fall away
whom God doth call to heavenly day.
Then, watchful Guardian, spread thy wings and cleave the air,
haste hither to our home committed to thy care;
drive thence each noxious ill that might the soul infest,
nor suffer danger here to rest.
Now to the holy Three your praise devoutly pour;
His glorious Godhead guides and governs evermore
this triple fame; to him ascribe we all our praise
who reigns through everlasting days. Amen.