What does it mean that the Federal Reserve will "roll over" the principal of all maturing Treasury bonds from December?

On October 30th, the Federal Reserve's FOMC statement mentioned that starting from December 1st, it will "roll over" the principal payment of all US Treasury bonds that are due. This sentence refers to the Fed's balance sheet operation mechanism, which means: from December 1st, if the Treasury bonds held by the Federal Reserve mature, it will not withdraw cash (reduce the size of its debt holdings), but will reinvest these funds in new US Treasury bonds, which is equivalent to extending the holding period and maintaining the size of assets unchanged, that is, ending the shrinkage of the balance sheet. The Federal Reserve holds a large number of US Treasury bonds on the balance sheet, and when these Treasury bonds mature, the Federal Reserve will take back the "principal" cash. At this time, it can do two things: ① do not roll over (no more investment), that is, take back the cash after maturity and do not buy new bonds, which is equivalent to reducing the size of the debt holdings, that is, shrinking the balance sheet; ② roll over (reinvestment), that is, buy the same amount of new government bonds after maturity, maintain the size of the debt holdings, that is, stop shrinking the balance sheet. Stopping the balance sheet is usually seen as a signal that monetary policy has shifted to easing or at least an end to the tightening cycle.