In complete honesty, one can say that the test identifies with an entire life's worth of knowledge. It essentially pulls from 3 different aspects. First, it draws from concrete facts that were acquired from all areas of a person's educational career. Secondly, it draws from a person’s ability to comprehend and use context clues to make assumptions. Lastly, it draws from a person’s physical/verbal skills to see if they can properly administer those more physical aspects. Overall this is why people have identified it as the “SAT on steroids.”
Candidates taking the ASVAB are given a AFQT (Armed Forces Qualifying Test) score which is simply a combination of your scores from four tests (Arithmetic Reasoning, Mathematics Knowledge, Word Knowledge, and Paragraph Comprehension). This AFQT score is represented as a percentile (from 1-99) which depicts how well you scored compared to other test takers. For example, if your score is a 57, this means that you scored better than 57% of the other test takers. The AFQT score is used to determine whether you are qualified to enlist in the U.S. Armed Forces.