This is the 7179th most frequent Polish word.
jagiellonię
"Jagiellonię" is the accusative form of "Jagiellonia," which refers to Jagiellonia Białystok, a Polish football (soccer) club.
The word 'Jagiellonię' refers to the accusative form of 'Jagiellonia', which is the name of a football club, used as a direct object in the sentence.
Jagiellonię uważam za jeden z najlepszych klubów piłkarskich w Polsce.
I consider Jagiellonia one of the best football clubs in Poland.
Here, 'Jagiellonii' is in the genitive case, indicating possession (Jagiellonia's match).
Czy widziałeś ostatni mecz Jagiellonii?
Did you watch Jagiellonia's last match?
The term 'Jagiellonii' is in the dative case, used as the indirect object of the verb 'kibicujemy' (we support).