Socionics is a theory that emerged from Jung's work. It is like a parallel to MBTI. It can give you a whole new perspective about cognition and information process, and give you a fresh understanding of those models.
1) If you want to learn more about it, you can visit wikisocion. Theory → Model A ; Information elements, Functions. You have the basics here.
2) If you want to pass a test, you can try out this one. My advice is that tests will give you an estimation of your actual type. Don't rely too much on it, but it can still give you an idea.