There is nothing; to have nothing. Used to say that nothing exists or one has nothing (casually often 'nanmo nai').
冷蔵庫を開けたら何もないので、買い物に行かなくてはならない。
When I opened the fridge there was nothing, so I have to go shopping.
財布にお金が何もないから、今日は出かけられない。
There's no money in my wallet, so I can't go out today.
その部屋には何もない壁がひとつだけある。
That room has just one bare wall with nothing on it.
そんなに気にすることはないよ。実際、なんもないから。
You don't need to worry so much. Actually, there's nothing (to worry about).