In property law this is the right of a creditor, usually the mortgage lender, to receive cash payment to cover the debt if the property is sold.
In some cases you may have borrowed further money against the value of your home, or guaranteed a bank overdraft with your home - the financial institution is described in this instance as having a second charge on your property - putting them in line to benefit from the sale after the outstanding mortgage has been settled.
Find out what sort of credit is right for me? and details about charge certificates.