So, this is a big one. Depending on a usage, it can mean a zillion of different things. These I could think of are: - to amplify a request or an order. "Pójdź *no* tam" is much more serious than a simple "Pójdź tam" (Go there) - to refer to previous parts of a conversation. "Poszedł na imprezę, *no* ale wyszło jak zwykle" (He went to a party, but it turned out as usual.) You can say it without "no" but using it suggests that you are Polish. - synonym of yes. "Idziesz do domu?" "*No*." (Going home? Yup.) It's more "yup" than "yes", rather informal confirmation. - kinda synonym of hooray. "No tak" is a good example. Imagine a detective movie or book and the main character trying to solve the case. He's just on the edge, and then he understands everything (the eureka moment). That's the situation when he might drop "No tak." - showing compassion or appreciating an accomplishment. In this case "No widzisz". The first use might be when a girl is telling her friend about a recent breakup and the friend goes "No widzisz". Not meaning too much, but rather an act of active listening. For the second one imagine a kid really not wanting to try something. Dad tells the kid "Try it, you won't regret it". After many convincing the kid finally tries the thing and loves it. Dad then says "No widzisz" - in this case "I told you so." or "Wasn't so bad, was it?" I'm sure there are many other uses of *no* but can't think of any more. To conclude, it is a connective word. It allows for a smoother, more fluent conversation.