Translation:To be born
Given that a lot of the sentences in the number skill are "we were born..." "you were born..." etc, introducing the verb to be born here does make some sense.
I'm assuming this and the "kwanza," "mwisho," etc. are because you often use numbers for ages and years. It might be good to have some combinations of millions and thousands and hundreds in here. E.g "[mwaka wa] elfu moja mia tisa tisini na tano" - 1995