With split funding, the card processor divides each batch of card sales. The funder's holdback percentage goes straight to the funder, and the rest is deposited in your account. You never handle the funder's share, and you do not have to keep a balance ready for a debit.
Because the split follows your card volume, it matches the design of a merchant cash advance closely: slow days send less. It usually requires a processor the funder works with, which can mean switching processors or agreeing not to change processors until the advance is paid.
Split funding covers card sales only. If much of your revenue arrives by cash, check or ACH transfer, a funder may prefer a fixed ACH debit instead, and your payment will no longer adjust on its own.