It just means that your monthly mortgage payment is to be paid directly by you and that the Trustee will not be making that payment (although arrearages may well be in the Plan).
I concur with atty Whitaker. Your monthly mortgage payment is not being included in your Chapter 13 Plan payment. You are responsible to pay the monthly mortgage payment directly to the mortgage holder. If you have an attorney, it will be explained to you more fully. If you do not have an attorney, you're facing an uphill battle trying to successfully complete all the obligations associated with navigating this legal morass. All pre-confirmation mortgage payments must be verified as having been paid to the mortgage holder by using a special form approved in your district. Good luck.
Monthly Ongoing Mortgage Payment refers to your normal monthly payment as opposed to any amount necessary to cure the delinquent payments. As indicated by the other attorneys, this amount is to be paid directly to the lender. The payments need to be made in full and on time. This is a benefit to you and your other creditors because if you paid it through your plan to the trustee, the trustee fee would increase.