ezept, I judge from another answer of yours that you are in the US, so I'll forgive you. The Royal coat of arms is displayed in courts and other official places (though not nearly as widely as the flag in the US), and it carries the letters ER, which puzzle some people. As dorset says, they stand for Elizabeth Regina, Latin for Elizabeth the Queen.
The name Saxe-Coburg-Gotha became that of the British Royal Family in 1840 with the marriage of Queen Victoria to Prince Albert, son of Ernst, Duke of Saxe-Coburg & Gotha. Queen Victoria herself remained a member of the House of Hanover.The only British monarch of the House of Saxe-Coburg-Gotha was King Edward VII, who reigned for nine years at the beginning of the twentieth century. King George V replaced the German title with Windsor during the First World War. The name Saxe-Coburg-Gotha survives in other European monarchies, including the current Belgian Royal Family and the former monarchies of Portugal and Bulgaria. The present Queen was born Elizabeth Alexandra Mary of York.
She is Elizabeth XVII of Piddletrenthide in Dorset, which has had a continuous line of Queen Elizabeths since the 15th century, but Elizabeth II of the rest of the UK. WVNBIVDB