This is the 16746th most frequent Russian word.
славянских
"Slavic."
Here, 'славянских' is used as an adjective describing 'народов', indicating the nations belonging to the Slavic heritage.
Я изучаю историю славянских народов.
I study the history of Slavic peoples.
In this case, 'славянских' is modifying 'ремеслам', referring to traditional crafts associated with the Slavic culture.
Это музей посвящён славянских ремеслам.
This museum is dedicated to Slavic crafts.
The term 'славянских' describes 'языках', specifying that the languages in question are within the Slavic group.