What is the value of a NE shilling with XII on it?

Answer 1

You've almost answered your own question. The word COPY is required by law to appear on all replica coins so that they are not treated as counterfeits. Whoever manufactured your coin did not intend to deceive anyone and they followed the law correctly.

It's almost certainly cast or struck in some base metal, and probably sold for a couple of bucks as part of a set of replica colonial coins.

The XII indicates that the face value of the coin is 12 Pence (or One Shilling). This was a common pratice with 17th century British Coins.

Answer 2

If genuine, its value is considerable. However this coin has been widely copied and counterfeited, so it's not likely that you have a genuine one. Look for the word COPY or COP somewhere hidden in the design. Newer legitimate copies for collectors are required to carry that marking; however, that law was not in effect years ago. Plus, a counterfeiter (as opposed to a copyist) will be very unlikely to mark his coins!

If you don't see the word COPY you could take the time to have it appraised but you will probably have to pay someone for that service.