This is not examinable in Paper F2 – it is Paper F3 where it is examined.
If you mean F3, then you really should watch our free lectures on inventory, because this is all explained there and I really cannot type out all the lectures here!
NRV is the expected selling price less any further costs that will be needed in order to be able to sell them.
(Our free lectures are a complete course for Paper F3 and cover everything needed to be able to pass the exam well)