After a customer makes a purchase with WooPayments, the funds from that transaction are placed into your account balance.
Normally, funds are subject to a pending period, after which they’re made available for the next scheduled payout. (You can change the payout schedule if you wish.) There are no extra fees for these regularly scheduled payouts.
With Instant Payouts, you can request some or all of your available balance to be paid out immediately, up to a daily maximum. These payouts are subject to an additional fee, but the funds will arrive within minutes. Please see the linked documentation on Instant Payouts for more information.