This is the 1664th most frequent Polish word.
piłką
The Polish word "piłką" means "ball" (instrumental case).
'Piłkę' is the accusative case of 'piłka,' used as a direct object of the verb 'grałem'.
Grałem w piłkę z kolegami.
I played ball with my friends.
'Piłką' is in its instrumental case, used to indicate the means or instrument of an action (e.g., what we used to play).
Dzisiaj bawiliśmy się na boisku piłką.
Today we played with the ball on the field.
'Piłką' is again in instrumental case, used to indicate the object being thrown.