What does Yuvan mean?
From Sanskrit yuvan (युवन्), 'young, youthful', and as a noun 'a youth, young man'; the dictionary sense also extends to 'strong, healthy'. A well-attested classical word.
What does Ayush mean?
From Sanskrit ayus (आयुस्), 'life, vital power, long life, longevity'. A blessing-name wishing the child a long life.