The disney dinning plans is a way to prepay for your meals. There is no real money savings, its more of a budgeting tool. There are a few different plans to choose from, all based on # of days. They include vouchers for various amounts ($5,10,15, character meal, and breakfast in the park). They come in a little book, and are used to pay for food. There are a few rules: No change is given. So, if you spend $13 you are better off to give $10 voucher and $3 cash, not a $15 voucher. Vouchers from various books can be combined, but can't be tore about before you get to the cash register. Some vouchers ($5 snack) can only be used in the parks, not at the hotels, and oddly include tax so they are really worth $5.32. None of the others inculde tax.
Most people consider them a hastle. My family likes them because it we can prepay and cut down our out of pocket money while at the park. We are horrible savers.