"Are they humans or sheep?"
Translation:Zijn ze mensen of schapen?
Because the plural form in English is the same as the singular. In Dutch it's different. So you have to pay attention to the rest of the sentence. The sheep are eating grass = De schapen eten gras. (plural) The sheep is eating grass = Het schaap eet gras. (singular)
An exception could be: "The cows and the sheep are eating grass". This could translate to "De koeien en de schapen eten gras." OR "De koeien en het schaap eten gras." In the last example, it depends on the fact if you know if there are more than one sheep, which you could deduct from context, but not from a single sentence.