What does my PSAT score officially mean?

I just found out today that I ranked in the 30th percentile on the PSAT. I took the PSAT last year, but I lost the papers with the overall info, so I just got my percentile score from my guidance counselor today. I honestly didn't take the test too seriously, because I really just guessed and even left some answers blank (the test was soooooooo boring). I'm actually a pretty good student with slightly above average grades, but I'm feeling a little concerned as to what a 30th percentile ranking really means and what it projects for me on the SAT, because I'm expected to take the SAT in the spring.