This is the 51st most frequent Japanese word.
何
"何" means "what."
In this sentence, '何 (nani)' is used as an interrogative pronoun meaning 'what' to ask about the activity being done.
何をしていますか。
What are you doing?
Here, '何 (nani)' is used as a relative pronoun meaning 'what' in the context of indirect speech.
彼が何を言ったのか分かりません。
I don't understand what he said.
In this sentence, '何でも (nandemo)' is a compound word meaning 'anything.' It indicates a broad selection of options.