This is the 7476th most frequent Polish word.
kostaryce
"Kostaryce" is the dative or locative case of "Kostaryka," meaning "Costa Rica" in English.
In this sentence, 'na Kostaryce' indicates the location, referring to Costa Rica as a geographical entity.
Byłem na Kostaryce podczas mojej ostatniej podróży.
I was in Costa Rica during my last trip.
Here, 'na Kostaryce' reflects engagement or interest concerning Costa Rica, its culture being the focus.
Interesuję się kulturą na Kostaryce od dawna.
I have been interested in the culture in Costa Rica for a long time.
In this context, 'na Kostaryce' specifies where the action of residing occurs, highlighting Costa Rica as the place.