Your raw score is "scaled" to a curve of how the entire group of people taking the test performed (and in some cases, how everyone who took the exam over the past few years did). Thus, your final score is based not only on your individual performance, but on the performance of the testing group as a whole. Your MCAT score indicates how far above or below average your raw test score is.
The Verbal Reasoning, Biological Sciences, and Physical Sciences sections are scored on a 1-15 scale with a target mean and standard deviation of 8 and 2.5, respectively. However, in practice the target mean and standard deviation are not met exactly, since scores are assigned to try to meet certain other criteria (e.g. a 15 corresponds to the 99.9th percentile, or there are as many 10+ scores as 1st year openings).
The results should arrive in the mail 8 to 9 weeks after the test.