In simple cases the NRV of eg a piece of machinery is its scrap value or resale value.
In more complicated cases NRV accounts for the costs relating to sale. So, if a business was selling and old machine for $5,000 (whether for scrap or to somone who will use it second hand doesn’t matter), but it costs the seller $500 to uninstall it before it can be shipped, then the NRV is 5,000 – 500 = 4,500.