1Something; anything—used to refer to an unspecified thing, matter, or event.
何か食べたい。
I want to eat something.
鞄の中に何か入っている。
There's something inside the bag.
何か手伝えることはありますか。
Is there anything I can help with?
疲れたら何か甘いものを食べるといいよ。
When you're tired, it's good to eat something sweet.
誰か何か言った？
Did someone say something?
2Somehow; for some reason—used when a feeling or state occurs without a clear cause.
今日は何か落ち着かない。
I feel somehow restless today.
彼の話し方が何か気になる。
Something about the way he talks bothers me.
このスープ、何か味が薄い気がする。
This soup somehow tastes a bit bland to me.
3An interjection used confrontationally to mean 'What (is it)?' or 'Got a problem?', often in response to being stared at or challenged.
じろじろ見るなよ。何か？
Stop staring. What?
何か？文句があるならはっきり言えよ。
What? If you have a complaint, say it clearly.