What does the last の in "おどるのはたのしいのです。" mean/do?

Question

I'm having trouble understanding the grammar of this sentence:

おどるのはたのしいのです。

I understand it means, "Its fun to dance," but I'm struggling to understand why の is placed here: おどるのはたのしいのです。

Answer 1

It's something called an explanatory-の.

• What is the meaning of ～んです/～のだ/etc?
• Wasabi: Explanatory のだ (んだ)

So the last の turns "It's fun to dance" into "It's that it's fun to dance". This の is a kind of a nominalizer that wraps everything before it and forms a noun clause.

• 楽しい。
  Fun.
• 踊るのは楽しい。
  Dancing is fun.
• [踊るのは楽しいの]
  [that dancing is fun]
• [踊るのは楽しいの]です。
  (It) is [that dancing is fun].

Note that you need some context for this sentence to make sense. For example, when the listener is wondering why you're dancing, you can say this to explain the reason.