A more thorough explanation:

A mortgage deed is a legal document that establishes a mortgage on a property. It is a written instrument that is signed, sealed, and delivered by the borrower to the lender. The mortgage deed gives the lender a security interest in the property, which means that if the borrower fails to repay the loan, the lender can foreclose on the property and sell it to recover the debt.

For example, if John wants to buy a house but doesn't have enough money to pay for it, he can get a mortgage loan from a bank. To secure the loan, John signs a mortgage deed that gives the bank a lien on the property. If John fails to make his mortgage payments, the bank can foreclose on the property and sell it to recover the debt.