This is the 13579th most frequent Polish word.
pióro
"Pen" or "feather."
Here, 'pióro' refers to a fountain pen, used as a writing instrument.
Mam nowe pióro wieczne.
I have a new fountain pen.
In this sentence, 'pióro' is used to mean a feather, a part of a bird's body.
Na ziemi znalazłem ptasie pióro.
I found a bird feather on the ground.
This use of 'pióro' specifies a pen, emphasizing its artistic use.