This is the 17159th most frequent Polish word.
zabroniony
Forbidden.
Here, 'zabroniony' is used as an adjective to describe the restriction of access to a specific location.
Wstęp na ten teren jest zabroniony.
Entry to this area is prohibited.
In this sentence, 'zabronione' indicates that a specific action, smoking, is not allowed within the premises.
Palenie papierosów w budynku jest zabronione.
Smoking cigarettes inside the building is prohibited.
Here, 'zabronione' is used to refer generically to activities or actions that are not allowed as stated by the sign.