An upper arm blood pressure monitor is a blood pressure monitor which you warn on your upper arm, at the level of your heart. That way, you'll get an accurate reading of both your blood pressure and heart rate. The devices are larger than the monitors which you ware around your wrist, so the data is easier to read. In addition, they often have extra functions, like a notification in case of a wrong application. A blood pressure reading via the upper arm is more accurate than a blood pressure reading via the wrist.