This is the 234th most frequent Serbian word.
неко
Someone.
In this sentence, the word "неко" acts as an indefinite pronoun meaning "someone" to refer to an unspecified person.
Неко је оставио тај пакет испред врата.
Someone left that package in front of the door.
In this instance, "неко" is used conditionally to reference any person who might inquire, thus serving as an indefinite pronoun.
Ако неко пита о овоме, реците да сам отпутовао.
If someone asks about this, say that I have traveled away.
Here, the word "неко" is in the accusative form "неког" and translates to "someone," used in a question seeking information about a person.