I have a sister named "Eve" who Sarah adores.
Sarah: Daddy, why is it called "Christmas Eve?" Why does Eve get her own Christmas?
Robert: Well Eve is her name, but when we call a day a name and then "Eve" it means the day before.
Sarah: So the day before my birthday would be "Sarah's Birthday Eve?"
Robert: Well..I guess technically.
Sarah: *thinks on this for a bit*
Sarah: Daddy, why is Eve called "the day before"?