This is the 77th most frequent Urdu word.
جن
"Jinn" - A supernatural being or spirit in Islamic and Arabian mythology, often capable of influencing humans.
Here, 'جن' is used as a relative pronoun to connect the clause to its antecedent 'کتاب' (book).
یہ وہ کتاب ہے جن کے بارے میں میں نے بات کی تھی۔
This is the book which I mentioned.
In this sentence, 'جن' refers to supernatural beings, commonly known as spirits or genies in English.
کچھ لوگ کہتے ہیں کہ جن انسانوں کے ساتھ بھی بات کر سکتے ہیں۔
Some people say that spirits can also talk to humans.
'جن' is employed as a relative pronoun to link the clauses, referring to 'عمارت' (building).