none, nun

None or none means not any, not one, or no part--
We wanted to rent a movie, but none of them looked interesting.
We ate all of the apples; there are none left.
That is none of your business.

Nun or nun ( rhymes with none ) means a female member of a religious order--
You may recognize a nun by the long habit that she wears.
She wants to be a nun when she grows up, but her mother wants her to marry and have children.

Now that you know that, you can say--
"That old nun still teaches in the Catholic school, but there are almost none of her order left."