When i hear that question, its only natural for me to think that whatever is to be discussed should be something that
could make you regret getting married to this person, something that
could have made you change your mind on spending the rest of your life with this person
With that said, here are some things i can think of:
Likes
Dislikes
Values
Family (kids,?)
Religion?
Future plans
Past life
finances definitely. how to share money and bills
. . . and the list is endless!