1. A translating apparatus of an image forming system, comprising: a translating unit of the image forming system for translating document data into another language; an output unit for outputting the translated document data translated by said translating unit in printed form; a mode setting unit for setting the translating apparatus in a first mode or a second mode; and a controller of the image forming system; wherein, in a case where the first mode is set, said controller controls said translating unit so as to translate the document data into a plurality of languages different from one another and different from an original language of the document data, and controls said output unit so as to output the translated document data by language groups of printed documents, the language of each language group of printed documents consisting of one of the plurality of languages, and wherein, in a case where the second mode is set, said controller controls said translating unit so as to translate the document data into a plurality of languages different from one another and different from the original language of the document data, and controls said output unit so as to output the document data by groups, each group of the document data comprising a printed document in the original language and printed documents of the translated document data translated in each of the plurality of languages with each of the printed documents being distinct from one another.