Can we also get "It is important you are happy!" as a correct answer? "That" is optional in the English version of this sentence.
Important is your happiness (noun) = Quan trọng là hạnh phúc của bạn!
Important is (that) you are happy (adjective) = Quan trọng là bạn hạnh phúc!
Sorry for my poor english:
Your happiness is important
It is important that you are happy
Interesting an entire sentence from one word...I would never have guessed it. Translations are very challenging at times.