Translation:Many young men live in America.
This sounds like a line from the Latin version of "YMCA".
"Iuvene! Dixi 'Iuvene!" (Young man! I said 'Young man!')
What is the difference between Multi and Multae?
Multi describes masculine nouns, and multae describes feminine nouns.
So what would the word for a young woman be?
Iuvenis can also be used for a young woman.
Why are these sentences all so ameri-centric. I personally find it very off putting
With macrons (cf. Wiktionary):
Multī iuvenēs in America habitant.