Unit 1.2 of Grammar - Sie and sie

Hallo alles! I was studying the last days the 1st chapter of the German Grammar and while I was making the exercises of the verb sein I had some questions that I wanted to raise concerning the Sie and sie. I wanted to know how we can distinguish whether is You formal (either singular or plural) or they. I understood very well that we can distinguish it from the meaning of sentence and that if it´s a formal You the Sie will be with capital S but there were some cases where the Sie was at the beginning of the sentence and from the phrase you can´t say clearly whether this is a You or they (as for example in the number 7 of the exercise - "Sie sind die Verlierer des Spieles." Let´s say that the English translation was not given to us. In case we were asked to translate the sentence from German to English how could we distinguish this? I asked my husband to explain this to me because he is German and I gave him this example and he remarked that there is a slight mistake on the translation. The translation says "You are the looser of the game." But "die" is either a feminine-singular article or a plural form, right? It couldn´t be feminine-singular because in this case the noun should have been "Verliererin" and the verb "ist", is that correct? So, it should be either "der Verlierer" or the translation should be: "You are the lossers of the game." I don´t know if I made myself clear. It´s not that serious but I just thought to mention it for the rest there to pay some attention on this and, if it´s indeed wrong, for you to correct it. Thanks for going through this message. Bis Bald! Paulina

Also, in case the correct translation is "You are the loosers of the game" what´s then the difference with "They are the loosers of the game." How can we distinguish it? Gute Nacht! Paulina