In Sinhala, we say “ආයුබෝවන්” (Āyubōwan) to greet someone politely.
It means “May you live long.”
Use it when meeting someone for the first time or in formal situations. But this is not what Sri Lankans actually use when they greet each other. Instead, a simple ‘kohomadha’ is used, which means ‘how are you’. And “ආයුබෝවන්” (Āyubōwan) is mostly used in formal situations.