Puppy dreams

What do puppies dream about? What happens in their little lives that they relive at night?
Bella sleeps in a crate at night. It's in the bedroom on my side of the bed so I get a front row seat to watch her when she sleeps.
The other night I took her out in the yard for her last potty break before we settled in for the night. There is a dog living in the house catty-corner to my house. I have never seen him but he sounds big. And he doesn't like Bella. Every time they are both out in their yards, he barks at her. This particular night he was barking very aggressively and actually growling. Bella was upset. I could see it in her posture.
But then the incident was over. The dog was scolded and we went inside.
That night I watched as Bella dreamed. Her little paws twitched. Her mouth wiggled. And then she started barking.
I'm sure she was being brave and telling that dog off in her dream, something she didn't do when she was awake.
So I guess dreams do the same thing for dogs that they do for humans - they help us resolve issues and we become what we wish we were in our waking life - brave and strong and solving all problems.