"He has his medication."
Translation:Er hat seine Medikamente.
Although several of the questions above ask about why the plural is used, I think that it might be the genitive case since it involves possession. Google Translate gives this same translation for both "He has his medication" and "He has his medications". It would be nice if a native speaker could help explain.
I could speculate about why the German sentence uses the plural, but I can't be sure.
One thing I can tell you though: it isn't genitive, for two reasons: 1) the genitive is used for the ‘possessor’ not the possessed thing, just like ‘'s’ in English; in this case you could say ‘he/er’ should be genitive, but possessive adjectives are used instead when the possessor is indicated by a pronoun. 2) the genitive would be ‘des Medikaments’; in no case is the genitive indicated by a simple -e ending, it can be -s, -(e)n, -(e)ns or simply nothing (for feminine nouns).
Actually this exercise shows up elsewhere as Er hat seine Medikamente, where the "seine" is the clue that it's plural. If you are translating from the English to the German, however, I think both Er hat siene Medikamente and Er hat sein Medikament (cuz Medikament is neuter) would be accepted. If not so, report it.