What does Nagendra mean?
Sanskrit compound of naga 'serpent' + Indra (as the suffix -endra 'lord, chief'), read as 'lord/king of serpents'. Hedge: the naga element is secure, and this split is the standard reading, but I could not confirm the full compound against a Sanskrit lexicon rather than name-reference sites, so treat the exact gloss as the common interpretation.
What does Sundar mean?
From Sanskrit सुन्दर (sundara) 'beautiful, handsome, lovely'. The masculine counterpart of Sundari.