You use no to acknowledge a negative statement or to show that you accept and understand it.
- not any, not a, or not one: there's no money left; no card in the file. 2. not by a long way; not at all: she's no youngster. 3. (followed by comparative adjectives and adverbs) not: no fewer than forty.
No is the ultimate negative: it means "not any," or "not at all," and it's also used to express a generally negative response. If there's no milk for your cereal in the morning, there's not a drop left.
