what does it mean when a person files a motion is correct an illegal sentence but the judge has it stricken?

Generally it means the court found some legal reason to treat the motion as if it had never been filed.  There could be any number of reasons for striking (i.e., treating the motion as if it had never been filed).  Sometimes the court explains in the order striking the motion the reason.  So you may want to review the court order to see if it gives any reason for striking the motion.  It could be as simple as failing to follow the rules pertaining to filing of motions.