i was exactly the same a month or so ago....DD DS DH DW i worked it out to be Disney daughter, son, husband wife...it had me stumped for ages..no doubt someone will correct me if i am wrong and I think PS is priority seating for meals.
I noticed you have just joined so welcome you will find everyone really helpful and dont worry about asking lots of questions as someone out there will be wanting to know exactly the same thing..
Have you booked a holday yet...me and the family are going in May on our first trip and I can't wait.