Basically it's just a conversation with people who know more than you. They'll point out what you did well and then ask you to elaborate on certain points that needed refining or clarification in the thesis. They might talk about things that could have been done differently or challenge particular ideas. Then they will tell you that the work is acceptable and you only need to revise this. Then it's over, you have a little more work revising to do, and voila.
no subject
Don't sweat it. This ain't nothin.