何か・
Add this particle to a question word to mean an unspecified person, thing, place, or time: someone, something, somewhere, or someday.
How it works
The question word sets the range of possibilities, and か leaves the particular member unidentified. This creates one noun-like unit rather than a direct question.
People, things, and places
Where other particles go
Treat the question word plus か as a complete unit, then add any particle required by the verb. In simple beginner sentences, the subject marker is commonly omitted after 誰か, and the object marker is commonly omitted after 何か. Other particles normally remain because they show a necessary relationship such as destination, location, recipient, or companion.
Adding a description
何か冷たいものを飲みたいです。
I want to drink something cold.
Analyze冷たいもの narrows the unspecified thing to something cold.
Someone or who?
A short sequence ending in 誰か does not always mean “someone.” In the first example, the particle after it shows that the whole unit means “with someone.” In the second, か closes an embedded question, so the meaning is “who that person is.” Look at the larger sentence, especially the verb that follows.