This is the 5948th most frequent Polish word.
zwanej
"Zwanej" means "called" or "referred to as" (feminine singular/genitive or locative case).
Here, 'zwanej' is used to provide additional information about the author, referencing her name.
Książka, którą czytam, jest napisana przez autora zwanej Marią.
The book I am reading is written by an author called Maria.
In this case, 'zwanej' introduces an identifier or title for the community being discussed.
Wspólnota, zwanej 'Nasza Grupa', organizuje spotkania co tydzień.
The community, called 'Our Group', organizes meetings weekly.
The usage of 'zwanej' here serves to specify the name by which the company is known.