This is the 756th most frequent Serbian word.
чачанског
The word "чачанског" means "of/from Čačak" (a city in Serbia) in English.
Here, 'чачанског' is an adjective derived from 'Чачак' indicating possession or relation to Čačak, describing 'краја' (region).
Лепота чачанског краја је непроцењива.
The beauty of the Čačak region is priceless.
In this sentence, 'чачанског' again describes the museum, attributing it as belonging to or representing the Čačak region.
Посетили смо музеј чачанског краја.
We visited the museum of the Čačak region.
Here, 'чачанског' is used to describe the dairy producer, indicating origin or connection to Čačak.