If you want to learn ABOUT math, Davis and Hersch's "The Mathematical Experience" is a fairly easy read about philosophy of math, how it is used, and a bit about studying math.
Eric Temple Bell's "Mathematics: Queen and Servant of Science" is a bit dated but an excellent history of math for someone interested in learning to do advanced math; the author's a bit biased towards algebra over analysis, number theory, and geometry, but not excessively so. Its biggest lack is only one short chapter on probability and statistics. This is not a particularly easy read since it covers things in some depth, but I think it is worth the effort.