A cash flow is a real or virtual movement of money:
Money is any item or verifiable record that is generally accepted as payment for goods and services and repayment of debts in a particular country or socio-economic context, or is easily converted to such a form.
ANSWER OR STRIP CHALLENGE W/ Cash Flow by Sheik T.V
a cash flow in its narrow sense is a payment, especially from one central bank account to another; the term 'cash flow' is mostly used to describe payments that are expected to happen in the future, are thus uncertain and therefore need to be forecasted with cash flows;
a cash flow is determined by its time t, nominal amount N, currency CCY and account A; symbolically CF = CF.
it is however popular to use cash flow in a less specified sense describing payments into or out of a business, project, or financial product.
A cash flow that shall happen on a future day tN can be transformed into a cash flow of the same value in t0.