What does Rohan mean?
From Sanskrit rohana (रोहण), 'rising, ascending, growing'. Some sources also give 'sandalwood'; the core attested sense is 'ascending/growth'. (Note: an unrelated Irish name Rohan/Rowan also exists.)
What does Aryan mean?
From Sanskrit arya (आर्य), 'noble, honourable, worthy'. The original sense is one of nobility and virtue; it is unrelated to later misappropriations of the term.