"Hello Kati, how are you?"
Translation:Szia Kati, hogy vagy?
"Szia" is an informal greeting, used mostly by young people. Probably translates more to "Hi". A neutral, less informal greeting would be "Jó napot" - although some people find it old fashioned. (on the other hand my Hungarian aunt disapproved of adults using "szia"). For close friends and family, I use "szervusz"