When you read a multimeter, three things matter: you picked the right function, the range is set correctly, and the number makes sense for what you're measuring. A 120-volt supply won't read right if your meter's on the wrong setting.
Hey, are you new to the trades? Here's something you may not know about reading your multimeter display correctly. Getting a number on the screen doesn't mean you have the right answer. You have to verify it. First, did you select the right function? Voltage, resistance, and current are completely different measurements. The meter doesn't know which one you need. Second, are you on the right range? Many meters auto-range, which is helpful, but if yours doesn't and you're on the wrong range, the reading will be wrong or the meter could be damaged. Third, does the reading make sense? If you're measuring a 120-volt supply voltage and the meter shows 1.2, check your function and range. A believable number can still be a false reading. Always verify before you act on what the meter tells you. Now that you know, you can help someone else know.
