What does Naava mean?
From Hebrew נָאוָה (na'avah) 'beautiful, comely, pleasant', as in the Song of Songs ('I am dark and beautiful'). The sense covers both 'beautiful' and 'pleasant/fitting'.
What does Shifra mean?
From Hebrew Shifrah, from the root sh-p-r meaning 'to be beautiful/fair, to please'. Borne by one of the midwives in Exodus; traditionally glossed 'beautiful'.