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.
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.