Or singular formal. Like vous in French, σου is like te, only singular informal.
I think "y'all" should be acceptable in addition to "you" for σας since it's the closest English equivalent. I know that isn't a proper English term but it's what makes the most sense to me in distinguishing between σας and σου. There is no plural form of "you" in modern English other than the informal "y'all". It used to be "ye" in middle English. Let's adopt "y'all" Duolingo!
Indication of the used pronoun:
So basically i understand that σας is the second object of the sentence? Is this known as the genitive form? Thank you
What I meant is that the dative indicates who or what receives the action of the subject: in the example "you" receive the action of reading because she reads for you. Another way of calling it is "indirect object".
That is correct, see the pronoun declension here https://en.wikipedia.org/wiki/Modern_Greek_grammar#Personal_pronouns
She reads them a newspaper? I thought σας could translate as them...