The name Milla is a girl's name of Polish origin meaning "young ceremonial attendant". Milla and is often added to lists like Names to Substitute for Emily and discussed in our forums with posts like "Makeover name game: from one gender to the other".
From the experts:
Milla, or Mila, can actually be short forms of many names that end or begin in mila throughout Eastern Europe. Milla Jovovich is a Ukaranian-born actress and supermodel. Another idea, newly fashionable in Europe: Millie.