The concept
Payout is the exit: the moment the available balance on the platform turns into money in your bank account. It happens after two filters, the withdrawal period and the rolling reserve.
In an international operation, the payout still goes through foreign exchange, and that's where costs show up that weren't in the fee table: FX spread, transfer fee, and sometimes an additional settlement period.
How it shows up in practice
You're running an infoproduct store with regular sales. Each sale reaches the platform, but it doesn't go to your bank account the next day. First comes the withdrawal period, then a security hold locks away a percentage of the value to cover possible chargebacks. Each of these filters takes money out of your immediate reach, damming up the cash flow you could reinvest in advertising.
Your margin is my opportunity.
When the withdrawal finally goes out, if your operation is international, it still goes through a currency conversion that takes another slice in spread and banking fees. Knowing exactly how long it takes from final payout to your bank account is critical for budgeting how much capital you need to set aside to keep the operation running.