If you say something the same way they say it in the capital, everyone in the whole country will be able to comprehend what you're trying to say. If you try to speak in your hometown's dialect no one will. But everyone can comprehend what you want if you use the capital's dialect to say it.
Now that the townspeople finally comprehend what you were trying to say, they sell you the row (りょう) boat you were trying to buy. You were using the wrong word, but りょう is what they needed to hear to understand you, and now you can row your way back home.