Someone
noun
誰 is who, 誰か is like asking "who?" If you don't know who it is, you just know it's someone.
The reading comes from the reading you learned with the kanji.
誰かがいる
someone is there
誰かがする
someone will do it
誰かがしてくれる
someone will do it for me
誰かにもらう
to receive something from someone
誰かに聞く
to ask someone
誰かに伝える
to tell someone
誰かの手
someone's hands
誰かの家
someone's house
誰かの助け
someone's help
誰かを待っている
to be waiting for someone
誰かをさがしている
to be looking for someone
誰かをしあわせにする
to make someone happy
「あ、あそこに誰かいる。」「え、誰もいないよ？」
"Oh, there's someone over there." "Uh, there’s no one there…?"
誰かに聞いてみよう！
Let's ask someone!
チームの誰かが代表として相手とじゃんけんします。
Someone on the team will play rock Rock-Paper-Scissors with the other party as a representative.