This is the 13585th most frequent Polish word.
piękności
"Piękności" means "beauties" in English.
In this sentence, 'piękności' is used as a noun in plural, referring to 'beauties', indicating the quality or things within the painting that are beautiful.
Ten obraz pełen jest piękności.
This painting is full of beauty.
Here, 'piękności' signifies 'beauties' in a broad sense, referring to beautiful aspects or elements present in the world.
Piękności świata są inspirujące.
The beauties of the world are inspiring.
In this case, 'piękności' is part of 'pięknością', used as a singular noun to describe a person who embodies beauty.