Accounts are used to track your business transactions. Accounts can track money coming in (Sales and Invoices), money going out (Expenses) and cash flow (Payments - Cash and Bank).
You can generate your business default chart of accounts on the Tyms web application.
Payments account are passed as the payment_type on the sales, expenses and payments resource.
N:B For bank payments, The uuid of the payment account is passed as the bank.