Are you talking about columns K and L in the Savings Budget? Or the Rollover Adjustment in the older Envelope Budget (which has been deprecated)?
The general idea is that if you budget doesn’t balance (i.e. expense budget !- income budget) then the rollover adjustment has an accrual that is kind of like a loan (that eventually needs to be dealt with). For example, if your expense budget totals $2000 and your income budget totals $1000, you have a rollover adjustment of -$1000 * 3 = -$3000 that you need to eventually pay back.