This translates to "My beautiful little girl."
Here are some other ways to say it in Portuguese:
* Minha pequena princesa: My little princess
* Meu anjo: My angel
* Minha florzinha: My little flower
* Minha menina dos olhos: My girl of my eyes (meaning: the apple of my eye)
* Meu raio de sol: My ray of sunshine
You can also use endearing nicknames or terms of affection that are specific to your daughter.