This is the 3721st most frequent Polish word.
kuczyńskiego
"Kuczyńskiego" is the genitive form of the Polish surname "Kuczyński," meaning "of Kuczyński" or "Kuczyński's."
In this sentence, 'Kuczyńskiego' is used in the genitive case to indicate possession, referring to something created by Kuczyński.
Książka autorstwa Kuczyńskiego zdobyła wiele nagród.
The book authored by Kuczyński won many awards.
Here, 'Kuczyńskiego' is in the genitive case, showing ownership or association with Mr. Kuczyński.
Odwiedziłem dom pana Kuczyńskiego w Krakowie.
I visited Mr. Kuczyński's house in Krakow.
In this sentence, 'Kuczyńskiego' is in the accusative case, referring directly to the person named Kuczyński as the object of the action of knowing.