He's young.

Dictionary
Examples

He's young, he knows a lot more than I do.	Il est jeune, il sait beaucoup plus de choses que moi.
He's young, too, and struggled a lot with addiction.	Il est jeune aussi, et a beaucoup d'addictions.
He's young, and he needs help growing up, that's all.	Il est jeune et il a besoin d'aide pour grandir, voilà tout.
He's young, he admires you, he works for you.	Il est jeune, il t'admire, il travaille pour toi.
He's young and he has a cause.	Il est jeune et il a une cause.
He's young, but he really is a doctor.	Il est jeune, mais il est vraiment docteur.
He's young and deserves the right to live.	Il est jeune. Il a le droit de vivre !
He's young and doesn't know what he does.	Il est immature, il ne sais pas ce qu'il fais.
Please, Tessa. He's young and he's from Manhattan.	S'il te plait Tessa. Il est jeune et il est de Manhattan.
He's young! He has good strong legs!	Il est jeune, il a de bonnes jambes !
He's young and he needs it.	Il est jeune et il en a besoin.
He's young, vital and healthy.	Il est jeune, vigoureux et en bonne santé.
He's young, but he has judgment.	Il est jeune, mais il a du bon sens.
He's young, but he'll grow strong.	Il est jeune, mais il deviendra fort.
He's young but he's wise.	Il est jeune mais il est sage.
He's young, but he's kind of smart.	Il est jeune, mais il est brillant.
He's young. What can go wrong?	Il est Jeune. Qu'est-ce qui pourrait tourner mal ?
He's young and healthy.	Il est jeune et en bonne santé.
He's young and wears a red t-shirt.	Il est jeune, il a un T-shirt rouge.
He's young, wealthy, tall, and good-looking.	Il est jeune, riche, grand et beau.