Pax Domini Sit Semper Vobiscum is a Latin phrase that translates "May the peace of the Lord be with you always". A breakdown:
PAX - "Peace" - in the Nominative Case
DOMINI - "of the Lord" - in the Genitive Case
SIT - "may it be" - (or "let it be") is a Hortatory Subjunctive.
SEMPER - "always" - is a pretty boring Adverb.
VOBISCUM - "with you" - a combination of "vobis" (Ablative of "vos" (meaning "you")),
and "cum" (meaning "with")
I first ran into this phrase with a Roman Catholic Priest
in training named Anthony. He happened to be in Latin Class
with me and signed my yearbook using it, saying it was a respectful Catholic parting blessing