My DFW-HKG flight was cancelled. I called the EP desk and asked for a refund, but instead got a flight credit. I click on it and it showed my cancelled trip.

a few questions.

1. What is a flight credit?
2. Why didn't the give me a refund (as AA canceled the route).
3. I had 4 SWU's attached and they have yet to be put back in my wallet.

any advice would be appreciated.