This is the 6633rd most frequent Japanese word.
ナニ
"ナニ" means "what" in English.
In this sentence, 'ナニ' is used as an interrogative pronoun meaning 'what'.
ナニが起こったのか、教えてください。
What happened? Please tell me.
Here, 'ナニ' is used as part of the expression 'ナニか', meaning 'something'.
その映画にはナニか特別なものがある。
There is something special about that movie.
In this sentence, 'ナニも' is used in a negative construction to mean 'nothing'.