1A prohibitive sentence-final particle attached to the dictionary form of verbs to mean 'Don't ...' (e.g., '行くな' = 'Don't go').
触るな！危ない。
Don't touch that! It's dangerous.
ここにゴミを捨てるな。
Don't throw garbage here.
勝手に入るな！
Do not enter without permission!
2A colloquial imperative (from 'なさい'), used after the stem of verbs or in short forms to tell someone to do something (more gentle/colloquial than a blunt command).
早く食べな、時間がないよ。
Eat quickly — there's no time.
宿題をちゃんとやりな。
Make sure to do your homework.
3An interjection used to get someone's attention or to call them ('hey', 'listen', 'look'), often initiating a request or comment.
な、ちょっと話があるんだけど。
Hey, I need to talk to you for a minute.
な、見てみろよ、あそこに鳥がいる。
Hey, look — there's a bird over there.
4A sentence-final particle expressing emotion, reflection, or seeking agreement ('... isn't it', 'I tell you', 'how...'), often lengthened (なあ).
いい天気だなあ。
What nice weather.
若いっていいなあ、うらやましい。
Being young is great — I'm jealous.
明日試験だな、準備はできてるか？
The exam is tomorrow, huh — are you prepared?
5A sentence-final particle expressing admiration or amazement (like 'wow' or 'ooh').
きれいな夕日だな、写真を撮ろう。
What a beautiful sunset — let's take a picture.
すごいな、その速さは信じられない。
Amazing — that speed is unbelievable.
6In Kansai dialect, a sentence-final particle used to request confirmation or agreement ('right?', 'isn't it?').
今日は暑いな、海でも行こか？
It's hot today, isn't it? Shall we go to the beach?
いい店やな、また来よう。
This is a nice place, isn't it? Let's come again.