A debt consolidation mortgage works by taking debt paid to several sources (like multiple credit cards), at high interest rates, and paying them with a single payment. This is usually at a much lower rate. Sometimes less than half of what you were paying before.
This is when you have a bunch of bills coming from a variety of sources like credit cards. All of these places that you have borrowed money from are charging you high interest rates. If you could pay off all of these bills with a consolidation mortgage with a much lower interest rate is could possibly save you a substantial amount of money.