A finger was a form of measurement used by the Spalgar species which inhabited Aantooine. It was based on the size of their finger from arm's length away and used to measure distances in the sky. This was particularly important for Spalgarian astronomy, which was important to the entire economy of Aantooine.
Behind the scenes[]
This is similar to the degree, as well as the smaller minute and second used in declination and right ascension while measuring the distance between objects in the sky.