Short answers, pulled from the story.
Subah was the term the Mughal Empire used for a province or state, applied to label its administrative subdivisions. The word is derived from Arabic and Persian, and other South Asian polities later adopted it too.
A subahdar was the governor or ruler in charge of a Subah, sometimes also called a Subeh. The title later evolved into subedar, an officer rank still used in the Indian and Pakistani armies.
Akbar created twelve subahs during his administrative reforms between 1572 and 1580. Conquests during his reign later expanded that number to fifteen.
There were 22 subahs during Aurangzeb's reign. He added Bijapur in 1686, Sira and Golkonda in 1687, and made Arcot a Mughal subah in 1692.
The term Subah is still used in Pakistan today, especially in Punjabi, Balochi and Urdu, where it refers to each of the country's four provinces.
A Subah was divided into sarkars, or districts, and each sarkar was further divided into smaller units called parganas or mahals.