How do you say happy birthday in kirundi?

In Kirundi, the official language of Burundi, you would say "Amahirwe y'umunsi mwiza" to wish someone a happy birthday. The phrase "Amahirwe" means happy, "y'umunsi" translates to of the day, and "mwiza" means good or beautiful. So altogether, "Amahirwe y'umunsi mwiza" conveys the sentiment of wishing someone a happy and beautiful day on their birthday in Kirundi.