This is the 9143rd most frequent Polish word.
szklarskiej
"Szklarskiej" is the genitive or locative form of "szklarska," which relates to a glassworker or something pertaining to glassmaking. It can also refer to "Szklarska Poręba," a town in Poland.
Here, 'Szklarskiej´ is used as part of the locative case indicating the place 'Szklarska Poręba´.
Wędrowaliśmy po lasach w Szklarskiej Porębie.
We were hiking through the forests in Szklarska Poręba.
In this sentence, 'Szklarskiej´ is in the genitive case because it describes the origin of the souvenir.
Kupiłem pamiątkę z Szklarskiej Poręby.
I bought a souvenir from Szklarska Poręba.
Here, 'Szklarskiej´ shows the possession in the genitive case, referring to 'Szklarska Poręba´ as the source of the view.