An RMD is the required minimum amount you must withdraw from a tax-protected retirement account. It is based on the account size and your life expectancy, and the point is that you must withdraw at least some money each year, you can't just leave it alone and save it for your kids.
An RMD is not a specific transaction, it is a dollar amount. For example, if your required minimum amount (RMD) is $5000, you would meet that if you withdraw $5000 on December 30, but you would also meet it if you withdrew $500 per month over the year, or if you withdrew $10,000 in June.
Money that is part of your minimum requirement can't be reinvested in another IRA or tax-protected account. If you withdraw less than your required minimum, you have to pay a penalty.
RMDs apply to most accounts when you turn 72, and to some inherited accounts.
If you have a pension that is paid out over your lifetime, it automatically meets the RMD rules, so answer yes, all the withdrawal is an RMD.
For other kinds of retirement accounts, your broker can tell you what your RMD was for 2021 and if you withdrew enough.
