This is the 424th most frequent Serbian word.
једне
"Jedne" is the genitive or accusative singular feminine form of "one" in Serbian.
In this sentence, 'једне' is used in the genitive case to describe a singular feminine noun ('ноћи', meaning 'night'), signifying 'one night'.
Било је једне ноћи кад је падао снег.
There was one night when it was snowing.
Here, 'једне' is used in a plural sense, referring to some people, highlighting an undefined set of individuals.
Упознали смо једне људе на путовању.
We met some people during the trip.
In this instance, 'једне' is in the genitive singular case, relating to the feminine noun 'пријатељице', meaning 'friend', and specifying possession or a relationship with 'њене', 'her'.