2006 Pontiac G6 Sending Unit

Engine Performance problem
2006 Pontiac G6 4 cyl All Wheel Drive Automatic 72K miles

The gas gauge is randomly going to "e" indicating that the car is out of gas, when there is gas, over 1/2 tank, car is chugging as if it is out of gas, 3 days random times. Engine light has not come on, and getting an error message in the window where the odometer is. I have been told it is the sending unit? My question, what is that, and could that be the culprit