This is the 1322nd most frequent Polish word.
niemiecki
German.
In this sentence, 'niemieckiego' is the genitive form of 'niemiecki,' modifying 'pochodzenia' to indicate German descent.
Osoby niemieckiego pochodzenia mieszkają tu od dawna.
People of German descent have lived here for a long time.
Here 'niemiecki' is inflected as 'niemiecku,' used in the instrumental case, referring to the German language.
Czy mówisz po niemiecku?
Do you speak German?
In this example, 'niemiecki' is used as an adjective to describe the origin of the film.