What does it mean when the letter 'o' appears before a noun or adjective as in 'o serye' or 'o kontre'

This Haitian Creole 'o' is borrowed from the French 'au' which could translate at, with, to the, etc... as in Café au lait, Coq au vin, Au contraire...

You will find this "o" in the following Haitian Creole expressions and others:
okontrè, o kontrè (borrowed from French Au contraire) → to the contrary
omwens, o mwens (borrowed from French Au moins) → at least
olye, o lye (borrowed from French Au lieu de)  → instead of
onondipè (borrowed from French Au nom du Père) → in the name of the father
Okap (borrowed from French Au Cap) → Cap Haitian
omilye (borrowed from French Au milieu) → between, among

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words