However, na-adj is different.
Usually, a na-adj is two kanji(like 親切、安全、危険), or one kanji+か(静か、明らか、確か), But there are other patterns too.
If you want to use na-adj to describe nouns, you need to add a な between na-adj and noun.
So if you see a な before a noun, then it means that you met a na-adj.
静か is a na-adj, its meaning is “quiet”, 部屋 is a noun, its meaning is “room”.
親切 is a na-adj, its meaning is “kind”, 人 is a noun, its meaning is “person”.