Call it Sleep is written entirely in English, but the dialog that is supposed to be spoken in Yiddish is in grammatical English, while the dialog that is supposed to be spoken in English is in very broken, Yiddish-influenced English (at least, the dialog spoken by recent Jewish immigrants from Eastern Europe, which if I recall correctly is the majority of the dialog).
So multilingual because they are speaking two different languages, and monolingual because everything is actually written in English; polyglossia because they are speaking two different languages, heteroglossia because the novel is written in different varieties of English, and translational because Yiddish is translated to English.
I doubt that the meaning of the sentence can be deduced without first knowing that Call it Sleep is actually multilingual polyglossia textually represented by translation into monolingual heteroglossia.