In Inside Out, Joy says:
Now we're talking! Let's go get our stuff from the moving van!
What does Now we're talking! mean?
Is it slang meaning something special?
It is informal/slang speech meaning "I enthusiastically agree with what you have said" or "I enthusiastically like the topic that you mentioned"
A:"Let's go to the beach."
B:"Now we're talking, I'll get my bucket and spade."
A:"And then the next day we went to the beach."
B:"Now we're talking, I love the beach."
Yes, it's an expression that belongs to the informal register of the English language. This is an offshoot of the equally common phrase now you're talking!. As for the meaning, you say now we're talking when you want to tell your listener that you really like what you hear. For example:
— I'm gonna pay you fifteen bucks an hour for this job. How's that sound to you?
— Now we're talking! I would love to do this job!