This is the 13668th most frequent Russian word.
немецкий
German.
Here, 'немецкий' is used as an adjective in conjunction with 'язык' (language) to specify the particular language being studied.
Я изучаю немецкий язык.
I study German language.
In this sentence, 'немецкий' is an adjective describing 'турист' (tourist) to indicate the tourist's nationality.
Это немецкий турист.
This is a German tourist.
Here 'немецком' is the prepositional case form of the adjective 'немецкий', used after the preposition 'на' (on/in) to refer to the language of communication.