One of the number and letter sequences on your tire is the uniform tire-quality grading (UTQG). The UTQG system is managed by the U.S. National Highway Traffic Safety Administration (NHTSA) and it gives you three pieces of information about your tires.
First, the numbers in your tire's UTQG tell you its tread wear. You want a higher number here, rather than lower, as this number gives you a rough idea of how long your tire will last. The government determines this number by testing your type of tire on a government track. Since you won't be driving it under the same conditions, don't read the number as a precise time span. Instead, the UTQG number is a pretty good relative gauge as to how long your tires should last.
Next is a letter (or two letters) that tells you the traction capabilities of your tire. The highest-rated tires (i.e. the tires with the best traction) have a rating of AA. The lowest UTQG traction rating is C. For purposes of setting these ratings, the government defines traction as the tire's ability to stop the car on wet concrete or asphalt. The UTQG traction rating doesn't reflect a tire’s ability to corner.
Lastly, the UTQG rating displays a single letter (A, B or C) reflecting the tire's temperature rating. Specifically, this UTQG rating tells you how well (or not) your tire can dissipate heat and how well it manages heat buildup. Excessive heat can cause your tire to wear down more quickly. Just as with the UTQG tread wear rating, the temperature rating the government gives a tire is based on specific conditions -- in this case, that your tire is always properly inflated. However, you can create more heat for your tires than the government tested for by under-inflating or overloading the tires, or driving at excessive speeds.