What does Santiago notice about the candy seller? [Is there anything significant here?]

What does Santiago notice about the candy seller? [Is there anything significant here?]

I'm kind of confused I know the candy seller is a truly happy person, and has a smile like the King of Salem.

The second part of the question confuses me the most, is the signficant part where seller and his assistant communicate in different languages, which makes Santiago realize there is a language of the universe.

Please help :)

The book is The Alchemist by Paulo Coelho