What is the meaning of a idioms vocabulary road?

There's no idiom that uses the phrase "vocabulary road." It seems you might be thinking of a different idiom or phrase, or perhaps you've misheard something.

Could you please provide more context? For example:

* Where did you hear this phrase? (A book, a movie, a conversation, etc.)

* What was the context? (What was being discussed?)

With more information, I can help you understand the true meaning of the phrase you're looking for.