This is the 6396th most frequent Polish word.
będący
"Being"
Here, 'będąca' serves as a present participle meaning 'being', describing the book's state.
Książka będąca na stole należy do mnie.
The book being on the table belongs to me.
In this sentence, 'będący' functions as an adjective that conveys a continual state or characteristic.
On jest będący zawsze chętny do pomocy.
He is always being ready to help.
Here, 'będący' describes the painting, indicating its state or role as a masterpiece.