Filing for bankruptcy puts into action something called an "automatic stay," which is intended to stop collection efforts against the debtor or their property by a creditor or collection agency. When a creditor asks for a "relief from stay," they're asking the bankruptcy court to lift the automatic stay so that they can, for example, repossess their collateral. E.g., an auto lender will ask the court for a relief from stay so they can enforce the lien against the car by repossessing it and selling it.