This is the 19th most frequent Persian word.
استان
"استان" means "province" in English.
The word 'استان' (province) is used here to indicate a political or administrative division of a country.
من در استان تهران زندگی میکنم.
I live in the province of Tehran.
In this usage, 'استان' (provinces) refers to multiple administrative regions within Iran.
این کتاب تاریخچهٔ استانهای ایران را توضیح میدهد.
This book explains the history of Iran's provinces.
Here, 'استان' (province) indicates the creation or establishment of a new administrative region.