The "state distribution" is the amount of the 1099-R distribution that is reported to a state (or states) as income; that state could be the one you live in or it could be the state where you worked and "earned" the distribution (e.g. pension)..
Depending on the type of distribution and your state of residence, a state distribution may or may not be taxable income to the state where it is reported. For example, if the payer reported all of the distribution to the state where you "earned" the distribution but you now reside in another state, then it is only taxable to the state where you live (if it has an income tax) - it is not taxable to the state where you "earned" the distribution.
If Boxes 14, 15 and 16 of your 1099-R are blank, then the payer did not report any part of the distribution to any state as income.
