What does Ranbir mean?
A Sanskrit/Hindi compound of rana (रण, 'battle') and vira (वीर, 'hero, brave one'), giving 'a warrior brave in battle'.
What does Nirav mean?
From the Sanskrit निरव (nirava), 'soundless, still', formed from nir- ('without') + rava ('sound, noise') — hence tranquil stillness. A genuine, if less common, classical formation.