What is the difference between "Du" and "Ni"?
How do I know when I should use the one or the other?

Question

Answer

Du is the second person SINGULAR, ni is the second person PLURAL. So depending if the subject you're using is one or more humans you use du or ni.
Du pratar svenska (you, singular)
Ni pratar svenska (you, plural)

Answer

What Elisa said! :)

"Ni" can also be used instead of "du", but only in formal situations. I don't think it's very common nowadays.

Answer

du - você
ni - vocês
Fácil 😶