'javaan' (जवान) reminds me of 'juvenile'.
And Joven in Spanish, Jeune in French, amazes me how similar some words are in different languages
Because they're all related to Hindi
And giovano in Italian?
why is it in plural (के and हैं) although the subject is singular (father)?
The plural form of things is also used to show respect, so you use them to refer to elders or people you haven't met yet, out of respect. Even if they are just one person