"Chúng tôi đọc tạp chí."
Translation:We read magazines.
A noun with no classifier or quantifier will typically refer to the noun group which in English is plural. Since there's nothing to quantify the noun "magazine", the sentence is actually referring to reading any magazine whether it be one or many. This also means there is no need for an article (i.e. the or a/an) in the English translation.
Note that this is unlike what lesson 1 may have taught us, but both the forms "magazines" or "the magazine" are accepted here.
Dear Lucy, are you busy? For a very long time I had not seen on duolingo. I am very happy when you come back duolingo. I really want to make friend and talk to you. Could we make friend, Lucy? Please, add my facebook to talk toghether.
Vietnamese speakers don't usually use plural, especially if the situation is too obvious. I suggest it's singular when there's the word ''một'' before the the noun (in Duolingo).