BofA Credit Card: Monthly Custom Pay Plan Fee (Fixed Finance Charge) meaning

I seen the above when applying for a BofA credit card What does it mean?? . In the footnote of the card it says: The monthly fee will be disclosed at the time the Custom Pay Plan is created, will never exceed a monthly fee of 1.72%, and does not change over the life of the Plan. The fee will be charged monthly until the Plan balance is paid in full. The total of all Monthly Custom Pay Plan Fees billed for any specific Plan will not exceed the sum of the original Monthly Custom Pay Plan Fee times the original total number of monthly payments established for the Plan. The fee for each Custom Pay Plan is based on the Plan duration, the amount of Purchases assigned to the Plan, the APR that would otherwise apply to those Purchases, and other factors.