Capstone Question (Psych)

I’m a junior psychology student, and I got pretty screwed over for registration, and I have basically 2 classes. I’m considering taking my capstone in the spring semester, rather than waiting until next year just because I can’t find anything else to add to my schedule. Is this a bad idea? I honestly don’t even know fully what a capstone entails, so any advice would be greatly appreciated!! Any other 300 level courses I could take to fulfill requirements? Thank you!