How do you say hello in thia?

There's no language called "Thia". Are you perhaps thinking of:

* Thai: "สวัสดี" (sa-wat-dee)

* Twi: "Afehyia" (a-fe-hi-ah)

* Tongan: "Malo e lelei" (ma-lo e le-ley)

Please clarify the language you're interested in, and I'll be happy to provide the correct greeting.