It's not Latin. It's French.
There is text under the lion and horse's legs. But the whole thing should read
Honi soit qui mal y pense ((Shamed be he who thinks ill of it) - motto of the Order of the Garter
Dieu et mon droit (God and my right) - motto of the English Monarchs
it's the royal Coat of Arms of the United Kingdom
Wikipedia says
The Royal Coat of Arms of the United Kingdom is the official coat of arms of the British monarch, currently Queen Elizabeth II. These arms are used by the Queen in her official capacity as monarch of the United Kingdom, and are officially known as her Arms of Dominion. Variants of the Royal Arms are used by other members of the Royal Family; and by the British Government in connection with the administration and government of the country. In Scotland, the Queen has a separate version of the Royal Arms, a variant of which is used by the Scotland Office.
cheers
Snoopy
PS; This coat of arms appear on some of the british coins too