I would describe it as a "holding area". When you receive a payment from a customer you go to Receive Funds and match the invoice off. The customer account then appears as clear. The money does not show up in the Bank Account until you Deposit the Funds. At this point you choose which bank account is to receive the funds from the drop down list and give the deposit a reference - I use the bank deposit slip number for cheques for bacs, DD, SO etc for other items which helps to recognise them on the bank reconciliation.
If you receive money from a non-customer go straight to Deposit funds, cancel the box that comes up, leave blank the Account from, Enter whichever nominal account you want the money to be credited to and put a description of what it is. The payment then goes straight to the bank.
I like this "holding area" because when I am paid by bacs I do not "deposit" the funds into the Bank account until I get the bank statement. It has been known for remittance advices to be sent but the money not transferred to the bank.