This is the 9157th most frequent Polish word.
szpak
Starling (a type of bird).
In this sentence, 'szpak' refers to the bird, starling, which is a direct use of the noun for the animal species.
W ogrodzie zobaczyłem pięknego szpaka.
In the garden, I saw a beautiful starling.
Here, 'szpak' represents the bird to evoke its characteristic coloring, which is used descriptively.
Jej włosy miały kolor podobny do piór szpaka.
Her hair was the color similar to the feathers of a starling.
'Szpak' in this sentence is again used to refer to the bird, emphasizing a potentially metaphorical presence.