This is the 13549th most frequent Polish word.
pietruszką
The Polish word "pietruszką" means "parsley" in English (instrumental case).
Here, 'pietruszką' is used as an instrumental case to describe an action involving parsley.
Dodałem pietruszką do zupy, aby dodać aromat.
I added parsley to the soup to enhance the aroma.
Here, 'pietruszką' is used in a figurative sense, employing a commonplace object (parsley) for a practical solution.
Zakryła mysią dziurę pietruszką, aby wyglądało estetyczniej.
She covered the mouse hole with parsley to make it look more aesthetic.
'Pietruszką' in this sentence explains a substitution, using parsley as the instrumental case to indicate change.