助詞N4
（疑問詞+）か
some- (somewhere/someone...)
Structure
疑問詞 + か（どこか / 誰か / 何か 等）
Explanation
Question word + か indicates an unspecified reference, "some-" (どこか, 誰か, 何か). It is also used in 〜かどうか (whether or not).
Examples
誰かがドアをノックしています。
Someone is knocking on the door.
何か食べたいものはありますか。
Is there anything you want to eat?
Note
Question word + か is affirmative (some-); question word + も + negative is total negation (no-).