none / nun are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
none: (noun) a canonical hour that is the ninth hour of the day counting from sunrise. (noun) a service in the Roman Catholic Church formerly read or chanted at 3 PM (the ninth hour counting from sunrise) but now somewhat earlier. (adjective) not any. (adverb) not at all or in no way.
nun: (noun) a woman religious. (noun) the 14th letter of the Hebrew alphabet.
none: n·AH·n
nun: n·AH·n
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)