What it tells you is that most (80%) of applicants fall into "this" range and a very small proportion (10%) fall below the minimum of the range. If you, too, fall below the 10th percentile for the school, then you have a good idea of what your chances might be at that school.
Keep in mind, too, that the admitted students who fall in that lowest 10% often have other things going on (low gpa but high MCAT, high gpa but low MCAT), super legacy/donor/political clout, exceptional story (non-traditional, military veteran or current service member) or remarkable come-back story (with a low total gpa but an amazing upward trend perhaps after recovery from a devastating illness, injury or other tragedy). This might account for 10students in a class of 100.... And keep in mind that the 3.2 gpa might come with a 40 MCAT and a 3.9 gpa might come with a 28 MCAT and both might end up in the lowest 10% of a class in one measure and within or beyond the 10-90th percentiles in another.