な, in hiragana, and ナ, in katakana, are Japanese kana, which each represent one mora.

The hiragana な is made in four strokes, the katakana ナ two.

Both represent [na].

な and ナ originate from the man'yōgana 奈.

な is used as part of the okurigana for the plain negative forms of Japanese verbs, and several negative forms of adjectives.