Appears to be a Minh Mang Thong Bao with Confucian inscriptions on the reverse, from the Minh Mang era (1820-1840), but I suppose it could also be a reproduction made at a later time period.
You can read more about the meanings of your reverse variant in this article by François Theirry, on page 383, chapter 4.25.
The Confucian message on Vietnamese coins - François Theirry
http://royalnumismaticsociety.org/N..._theirry.pdf