Can anyone tell me what Haku'ia means in Hawaiian?

Hello! Apparently you have 2 different questions. As far as I can tell, kauiis not a word in Hawaiian; maybe you meant Aina Kauai, which would make perfect sense--it means Land of Kauai (Kauai is one of the Hawaiian islands.) See the definition for Aina here.

As for haku'ia or Haku'Ia, haku means lord, and ia is Hawaiian's third person singular--he, she, or it. It would usually be capitalised, as in your example, when referring to God or the Lord Jesus. Compare John 21:20 in Hawaiian and in English.