int rate swap

Sir,I have two questions about the interest rate swap
Usually the examiner answer will included “At the start of the contract, the value of swap will be zero” OR “At the start of the swap, the net present value of the swap receipts based on the variable rates from the bank will be the same as the costs based on the fixed amount paid to the bank. ”

1)What does the NPV mean that? Is it mean one gain from the rate will be offset by another one loss?

2)What is the value of the swap?

Thanks