What does Belle mean?
The French word belle 'beautiful', feminine of beau, from Latin bellus. Used as a given name meaning 'beautiful' and also a short form of names like Isabelle/Annabelle.
What does Nadine mean?
A French elaboration of Nadia/Nadya, ultimately from Russian Nadezhda, from the Old Slavic word meaning 'hope'. The 'hope' sense comes through the Slavic root rather than any native French element.