While I haven't used the dining plan yet, will in Feb., this is my understanding:
You receive a credit for a snack, credit for a counter service and 1 table service credit per person for each night you stay.
So for 2 people for 5 nights you will receive a total of 10 in each category.
they can be used a variety of different ways over your stay. In other words, it isn't credited per day, but a lump sum given to you on the first day. The only caveat is that you can't use more in one transaction than you have people in your party. So, you can order 2 counter meals in one transaction, if you have 2 people on the plan.
Snacks are labeled with a little icon that you can find on the dining plan packet.
A quick service is a counter meal where you order and carry your tray to your table. You get an entree, drink and dessert.
A table service is a full service restaurant. You will be entitled to an entree, dessert and non-alcoholic drink (soda). Tax is included, but tip is not.
Some table service restaurants require 1 table service credit per person. Others, signatures, require 2 table service credits per person.
So day one, you may not want a snack, but a counter service lunch and then a counter service dinner. So out of the 10 credits in each category, you would have
left:
10 snack credits
6 counter service
10 table service
The next day, you have a counter service lunch and a signature dinner. So you would have this left:
10 snack
4 counter service
6 table service
I hope that helps a bit. I'm sure others with lots of experience will be able to provide more information.