Kí ni orúkọ rẹ̀? (kee nee o-roo-ko reh?)
Here's a breakdown of the words:
* Kí - What
* ni - is (copula)
* orúkọ - name
* rẹ̀ - its (possessive pronoun)
Other possible translations:
* Àwọn wo ni wọ́n pèé? (ah-won woh nee won pee?) - What are they called? (This is more literal, meaning "What do they call them?")
* Kí ló jẹ́? (kee loh je?) - What is it? (This is a more general question, meaning "What is it?" or "What kind of thing is it?")
The best choice depends on the context of your question.