Vos is an archaic pronoun that was used to address the nobility. Like
usted it was associated with a different verbal form, in this case the plural. You address a noble as if he was more than one person. I guess that's hard to appreciate in English that doesn't make a differece even in the pronoun: you for one you and you for multiple
yous.
Argentinian Voseo is using the pronoun but not the majestic plural. Instead they create a brand new form, altering the accent. I had no idea that it was so extended outside Argentina. That surprises me because I know people from many of the relevant countries and had not heard any of them using it, except Argentinians.
