"I see your windows."
Translation:Widzę twoje okna.
Why twoje okna, and not twoja okna? Does the plural make it appear feminine, but does not actually change the sex of the root word?
Any noun can "appear" feminine as in end in -a , masculine nouns in gentive, neuter nouns in genitive and plural, some masculine nouns in nominative ( mężczyzna=man, is the most famous)
also as @mixhal noted, polish plural has two genders, different than singular
Masculine personal - masculine nouns that describe persons
not masculine personal - all feminine nouns, all neuter nouns, masculine nouns that do not describe persons.