It's generally used to express:
* Acknowledgement: "Chur" can be used as a quick acknowledgement of something, similar to "Okay" or "Right".
* Gratitude: It can also be used as a way to say "Thank you".
* Agreement: Sometimes it's used to express agreement or understanding.
While "chur" is widely used in New Zealand, it's not considered formal Māori language. It's more of a colloquialism.