Exactly what it sounds like. A cash inflow means that cash is going into the company, and a cash outflow means cash is going out of the company.

When the outflow and inflow are equal.

The recording of an account payable does not create any current effect on cash flow, so it is neither creates an inflow or outflow.

Net cash flow is calculated as follows

Net cash inflow (outflow) from operating activities

Net cash inflow (outflow) from investing activities

Net cash inflow (outflow) from financing activities

Total cash inflow(outflow)

Add: Opening cash balance

Closing cash balance

Closing cash balance must be equal to cash balance in balance sheet.

Cost is the cash outflow of some activity to achieve higher cash inflow from some activity. Cash outflow is called the cost while cash inflow is called the benefit from specific activity. If cash inflow is morethan cash outflow then it is said that activity has more benefit then it's cost.