It can be used like that but without any context it will not be understood. For there, 'वहाँ' will replace 'वह' in this sentence.
Why does the word for women get pluralized (aurat, auraten), but the word for men does not?
Masculine nouns NOT ending in /ā/ do not change their forms in the plural. 1 kelā, 2 kele (1 banana, 2 bananas) - change 1 seb, 2 seb (1 apple, 2 apples) - no change
What is your nationality? I can see if, for example, you have a background in Pakistan you might have the intuition to expect "vo," but in this case, "ve" is indeed correct for Standard Hindi.
No that translation lacks the verb. The sentence वे तीन आदमी हैं। Those three men are., they are three men. Those three men would be वे तीन आदमी without हैं and that wouldn't be a sentence so would not have । (the danda, devanagari full stop/period)
Judging from the Q in your name (!) I'm guessing you have some Indian Muslim heritage and maybe an association with "Urdu." It's true that in Urdu, people don't care for a distinction between singular vo and plural vo. However, in the standardized/literary "Hindi," people make a distinction between singular vo (which they spell as vah) and plural ve. "Hindi" spoken on the street will be like "Urdu" in this sense, so one can question the value of learning this "ve" thing. Knowing it lies mainly in the fact that literary people do recognize it. It mean... that's why it's in this course; they didn't just make it up!