Here is an example of out-of-range behavior: Let's say you have set up a weight range from 0 to 10 lbs. Your customer wants to place an order that is 15 lbs, and no behavior has been configured. By choosing “Apply the cost of the highest defined range”, PrestaShop will apply the price conditions that you have set up for orders from 5-10 lbs If you choose “Deactivate the carrier”, then this carrier will not be offered to the customer in this case.
By "states", PrestaShop calls administrative divisions of a country. In the United-States, they are called "states"; in Italy, it's "province" (singular: "provincia"); in France, it's "départements" (departments); in the United-Kingdom, it's "counties".
Have states properly defined in your database helps with the carriers