MAC is a unique identifier for the network adapter in your PC. In the case of a laptop, there are often 2 (one for WiFi and one for cabled network connection).
Unless you have the security on your router set up to only allow known MACs, then you should not need this (most domestic users won't need to enter it). In any case if you are using a modern router that uses WPS, you should not need to concern yourself with this.
SImilar with VPN - unless you have deliberately set up a VPN, I can't see why you would need to worry about it.