Nosotros trabajamos. Nosotros means “we”. “Ustedes trabajan” means “you work”, ustedes refers to you as a plural. In Spanish you singular and you plural are different: “tú” is singular and “ustedes” is plural. “Nosotros trabajemos” is grammatically correct but it’s not the same tense as the original sentence as it’s in the subjunctive. “Ustedes trabajen” also refers to you as a plural, that is to say, the second person of the plural. And, apart from that, the verb is in the subjunctive.
