"Mia bella" is a phrase that combines two Italian words to create a unique combination and meaning. "Mia" is the Italian word for "my." "Bella" is the Italian word for "beautiful." When placed next to each other, these words change the overall meaning of the combination to "my beauty" or "my beautiful girl or woman." The phrase is often used as a term of endearment toward loved ones or children.
"Mia bella" implies that the subject is feminine, since the form of the noun is feminine. If the subject of the phrase were male, it would be written as "mio bello." The meaning would essentially be the same, although when translated to English someone might say "my handsome boy or man" instead. The Italian language also allows for the reversal of pronoun and noun in any sentence so that it reads "bella mia." The meaning remains the same in either case, and there is no distinction made.