What does relief from bankruptcy mean when your mortgage co. says it

I assume you're referring to relief from the automatic stay.  The automatic stay is what prevents creditors, including mortgage companies, from taking collection actions against you during your bankruptcy case.   If you fall behind on your payments (and for other reasons sometimes) the bank can seek "relief" from the automatic stay to allow them to pursue whatever remedies are available to them under your state's laws (such as foreclosure).