This is the 12207th most frequent Polish word.
małżeńskich
"Małżeńskich" means "marital" or "pertaining to marriage" in English.
Here, 'małżeńskich' is used as an adjective to describe 'finansów', specifying what type of finances are being discussed.
Musimy omówić kwestie małżeńskich finansów.
We must discuss the matters of marital finances.
In this sentence, 'małżeńskich' modifies 'praw i obowiązków', indicating that these rights and duties pertain to marriage.
Znaleźli dokumenty małżeńskich praw i obowiązków.
They found documents of marital rights and obligations.
'Małżeńskich' serves as an adjective here affecting 'problemów', explaining the problems are related to marriage.