Meaning
A bold letter A in a square, usually red, created to label blood type A. It also works as a standalone capital A or a top grade.
People use it in blood donation drives and health profiles, to show off an A grade, and to spell words with button letters: “Final result: 🅰️ in physics, finally” It pairs with 🅱️, 🆎 and 🅾️ when listing all the blood types.