TAKOBOTO

(particle used with na-adjectives)
What a strange man!

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わたしはきっとへんなひとだとおもわれてる。

I'm sure I'm thought of as an odd person.

かのじょはきれいなあしをしている。

She has beautiful legs.

しずかなレストランにいきましょう。

Let's go to a quiet restaurant.

な is used by na-adjectives to modify the word that follows them.
This is exactly the same way の is used with nouns to modify the word that follows them.
な derived from なる - and なる can still be used in some circumstances in the same way.

Amatuka

E.g. 車 - (a) Car.
Modify with な-adjective,
大きな車 - (a) Large car.
Modify with noun
フレッドの車 - Fred's car.

Amatuka

Note that the same word can often be used both as a na-adjective and as a noun.
Also quite a lot of i-adjectives can (with the i removed) be used as na-adjectives.
e.g. 大きい車 vs. 大きな車

Amatuka