This is the 8900th most frequent Polish word.
serbią
"Serbią" is the instrumental case of "Serbia," meaning "with Serbia" or "by Serbia" in English.
In this sentence, 'Serbią' is used in instrumental case to indicate the place through which the action of traveling occurred.
Podróżowałem przez Serbią podczas wakacji.
I traveled through Serbia during the holidays.
Here, 'Serbią' is also in instrumental case, expressing an interest in Serbia and its cultural aspects.
Interesuję się Serbią i jej kulturą.
I am interested in Serbia and its culture.
In this example, 'Serbią' is mentioned in context of a discussion, providing a topic related to Serbia's history.