This is the 2489th most frequent Polish word.
izraelu
"Izraelu" is the locative or dative case of "Izrael," meaning "Israel" in Polish.
The word 'izraelu' is used here as the locative case, indicating the location where the friend resides.
Odwiedzę kolegę, który mieszka w Izraelu.
I will visit a friend who lives in Israel.
The word 'izraelu' is used in this sentence in the genitive case, signifying possession (the culture belonging to Israel).
Kultura Izraelu jest bardzo interesująca.
The culture of Israel is very interesting.
In this sentence, 'izraelu' appears in the locative case, associated with the topic of discussion (history related to Israel).