One of the common meanings that の is used for, is referring back to a noun that has already been mentioned. In this way, it is very similar to ‘the one’ in English. This use of の regularly highlights the possession of something that has previously been asked about with この, その, or あの.

• この本（ほん）はたけしさんのです。
  This book is Takeshi-san’s one.
• そのペンは誰（だれ）の？あなたの？
  That pen, whose one? Is it your one?
• あの頃（ころ）の映画（えいが）は面白（おもしろ）いの。
  That era’s movies are amusing ones.

In these examples, it would also be grammatically correct to use the same noun following の. However, this is called 重（かさ）ね言葉（ことば） (word stacking/redundant words) in Japanese, and is considered a poor writing/speech habit. Despite this, it is important to know that this の is exactly the same as the possessive の (with the following word simply being left out).

• あの車（くるま）、あなたが乗（の）っている車（くるま）ですか。
  That car, was it the car you drove? (‘Car’ repeated, when の ‘the one’ should have been used instead)

From this sentence, it is clear that the repeated noun is not needed. Japanese is a language that avoids repeating words in many situations.