Further Advance
This is an additional loan by a lender to the borrower.
If you wish to raise money against the value of your home - go see your home lender.
A further advance to release more money on your home, is sometimes referred to as a second mortgage. It will usually be secured by the existing mortgage deed.
You may wish to take out a further advance to pay for property improvement, a new car, school fees, or to invest in a private business etc.
If the equity in your property (i.e. it's worth substantially more than the outstanding mortgage ) you'll be able to extend your loan - although not necessarily at the same interest rate as your existing home loan.