This is a Tibetan zodiac plaque of brass (the green patina indicates this) and gilt.
I submitted an image of the back inscription to an online Tibetan language forum in hope of getting a translation, but haven’t heard back yet.

My appraisal is based on looking at asking prices as well as hammer sales of similar objects. Below I have listed some links to some examples. Bear in mind that asking prices can be a useful guide but are not authoritative, especially on sites like ebay, where I found the majority of these pieces for sale. It is still useful to note some of the higher asking prices out there to get a sense of the market.

The hammer prices I did find were generally lower, but I also found fewer closed sales overall.
We can safely say it is worth over $100, and I think that the Fair Market Value would be somewhere around $200 to $300. I am considering the estimate on the $100 sale as well as the range of asking prices. I am also considering materials and complexity of design.

Here are some similar pieces I found:

Asking $260, Tibetan copper gilt zodiac plaque
https://ebay.to/2Te8l8K
Asking $690, Tibetan zodiac plaque, cloisonne accents
https://ebay.to/35cvWZT
Asking $720, Tibetan zodiac plaque, says it’s silver: see note below...
https://ebay.to/2RIYk2W
Asking $1056, similar
https://ebay.to/2TUUUuF and https://ebay.to/3pAHY92
Asking $870, more elaborate design and embellishments
https://ebay.to/3waM4XX
Asking $615, silver
https://ebay.to/354COsj

Note on Tibetan silver:
“Tibetan Silver is a silver-colored alloy consisting of copper with tin or nickel. Some items described as Tibetan Silver are cast iron that has been plated with the silver-colored metal.”
Source: https://www.thoughtco.com/what-is-tibetan-silver-608022

Hammer prices:
$100, described as 19th century, brass, pre-auction estimate $300-400
https://www.liveauctioneers.com/item/43196761_sino-tibetan-bronze-zodiac-plaque
$120, 20th c., brass
https://antiquebuddha.co.uk/sold/20thc-tibetan-zodiac-plaque-in-repousse-brass/
$350, gilt, cabochons
https://www.liveauctioneers.com/item/36730748_chinese-or-tibetan-gilt-copper-buddhist-plaque
$1200, very elaborate
https://www.liveauctioneers.com/item/22954462_chinese-or-tibetan-gilt-copper-buddhist-plaque