One of the roles that the particle
の can take in Japanese is replacing a noun that has already been mentioned, or one that has not been mentioned yet. In this way, it is similar to ‘the one that (A)’ in English. When using this expression, we will need to use
な before
の, when a
な-Adjective is being used.
-
可愛（かわい）いのは私（わたし）の犬（いぬ）です。
The one that is cute is my dog.
-
心配（しんぱい）なのはあなたです。
The one that is to be worried about is you.
When using this expression,
の will be followed by
は,
が, or
も, depending on what the speaker/writer wants to express.
-
安（やす）いのはあのペンだ。
The one that is cheap is that pen. (Without much consideration for other things)
-
熱（あつ）いのがこれです。
This is the one that is hot. (Specifically highlighting one thing out of several)
-
冷（つめ）たいのも好（す）きです。
I also like the one that is cold.
の may be used more than once in the same sentence, referring to the same noun.
-
ここにある車（くるま）の中（なか）で好（す）きなのはあの赤（あか）いの。
Out of the cars that are here, the one that I like is that red one over there.