This is the 9185th most frequent Polish word.
słowiańskiej
"Slavic" (pertaining to the Slavic people or culture).
The word 'słowiańskiej' is an adjective in the genitive case, modifying 'społeczności' (community), indicating that the community belongs to the Slavs.
Kultura słowiańskiej społeczności jest bardzo bogata.
The culture of the Slavic community is very rich.
Here, 'słowiańskiej' is used as an adjective in the genitive case, modifying 'Europy' (Europe), referring to Europe as influenced by Slavic history.
Czytał książki o historii słowiańskiej Europy.
He was reading books about the history of Slavic Europe.
In this usage, 'słowiańskiej' serves as an adjective in the genitive case, describing the type of culture represented, in this instance, Slavic culture.