There is a great Monty Python skit where someone pays John Cleese to have an argument. They have a silly converation just disgrees with anything the other person says:

But an argument isn't just saying 'no it isn't'.
Yes it is.
No it isn't!

This is a negation. (No it isn't).

A negation is where you say that someone isn't doing something, or that someone or something isn't a certain way: I am not singing. I am not a policeman. The sky is not green.

In English we can often negate a sentence using the word "not": I am going, I am not going. He is big, he is not big. She happy, she is not happy.

In Māori, the negations are a little more complicated because there are different ways to negate different things. A sentence with a verb ("I am going") is negated one way, but a sentence with a noun ("I am a teacher") is negated in a different way - and a sentence with a command ("Go away!") is negated in a different way again.

Let;s begin with a simple sentence:

Kei te noho ahau.
I am sitting

We negate this by doing three things.

Firstly, we put kāore at the start of the sentence. This is the word that is used to negate sentences with verbs.

Secondly, we are going to swap the words around in the sentence. Instead of saying kei te noho ahau, we are going to put the word ahau before the word noho. 

Thirdly, we are going to change kei te into i te.

So, the final sentence is:

Kāore au i te noho.
I am not going.

The sentence "I am singing" - kei te waiata au - is negated in the same way:

Kāore au i te waiata.
I am not singing.

Firstly, we have added kāore at the start to indicate that this is a negative sentence.

Secondly, we have swapped the order of the words around. Waiata is not at the end, and au is at the start, after kāore. And, instead of kei te we have i te: kāore au i te waita - I am not singing.