This is the 17672nd most frequent Turkish word.
şubesinin
"Şubesinin" means "of its branch" or "of its subsidiary" in English.
Here, 'şubesinin' refers to the 'branch' (specifically belonging to the bookstore), indicating possession.
Kitapçı şubesinin müdürü toplantıya katıldı.
The manager of the bookstore branch attended the meeting.
In this sentence, 'şubesinin' is used to denote possession, referring to the bank's branch.
Bankanın şubesinin önünde uzun bir kuyruk vardı.
There was a long queue in front of the branch of the bank.
'şubesinin' specifies the branch of the insurance company, showing a possessive relationship.