This is the 327th most frequent Polish word.
polskim
"Polskim" means "Polish" (as in the Polish language) in the instrumental or locative case.
Here, 'polskim' is the locative case of the adjective 'polski', indicating the language being discussed.
Czy mówisz w polskim języku?
Do you speak in the Polish language?
In this sentence, 'polskim' is the instrumental case of the adjective 'polski', used to describe the noun 'malarstwem' (painting).
Interesuję się polskim malarstwem.
I am interested in Polish painting.
Here, 'polskim' is the instrumental case of 'polski', referring to the characteristic of the noun 'krajem' (country).