ASE is the abbreviation for Automotive Service Excellence. ASE is basically an official license to be a mechanic.
In order to receive the ASE you must complete a series of training, obtain 2 years of experience in auto repairs, pass the specialty exam. You can pick among three types of specialties for ASE certification (breaks, heating and cooling, or suspension). You must retake (and pass) the tests every five years in order to keep a current certificate.
ASE seals should be posted outside of service stations. Sometimes customers look for the blue and white ASE seal because it ensures them that their car is being repaired by a highly qualified mechanic. When a mechanic possesses an ASE seal it says that the mechanic has knowledgeable pertaining to truck equipment, school buses (transit buses), engine mechanics, collision repair, and (medium and heavy) truck repair.