Realizing on the security refers to the process by which a lender enforces its rights over collateral or security that was pledged by a borrower in the event of a default on a loan or other financial obligation. This process typically involves the lender taking legal steps to seize, sell, or otherwise dispose of the collateral to recover the outstanding debt.
In the context of real estate, if a borrower defaults on a mortgage, the lender may “realize on the security” by initiating foreclosure proceedings. This allows the lender to take possession of the property (which serves as security for the mortgage) and sell it to recover the unpaid loan balance.