This is the 140th most frequent Serbian word.
неки
"Some" or "certain."
Used as an indefinite adjective indicating an unspecified or vague group of people.
Неки људи воле да читају књиге.
Some people like to read books.
Used as an indefinite adjective indicating an unspecified or unknown movie.
Видео сам неки филм синоћ.
I watched some movie last night.
Here 'неко' is used as a pronoun meaning 'someone' in an unspecified context.