This is the 7164th most frequent Polish word.
izerską
"Izerską" refers to something related to the Izera Mountains in Poland.
The word 'izerską' here is connected to describing something that belongs to the Izerskie mountain range.
W paśmie górskim Izerskim znajduje się wiele malowniczych szlaków.
There are many picturesque trails in the Izerski mountain range.
Here, 'izerską' modifies 'dolinie' (valley) to indicate that it pertains to the Izerska area.
Przyroda w dolinie izerskiej zadziwia swoją różnorodnością.
The nature in the Izerska valley astonishes with its diversity.
In this case, 'izerską' functions as an adjective qualifying the word 'wycieczkę' (trip), implying that the trip is related to the Izerski region.