What it means
何も〇〇ない expresses that not even one thing satisfies the negative predicate, so it means “not anything” or “nothing.” It is normally used with a negative verb or another negative predicate. The phrase often emphasizes the complete absence of an action or object, rather than merely saying that the action did not happen once.
Usage note
何も must normally be followed by a negative predicate. Do not confuse it with 何か, which means “something” or “anything” in questions and affirmative sentences.
How to use it
旅行中は何も買いません。
During the trip, I do not buy anything.
旅行中は何も買わない。
During the trip, I do not buy anything.
