Check Google & read about the definition. Long story short it is a HEGO (Heated Exhaust Gas Oxygen). This is referring to the sensor AFTER the Cataltic Converter.
Were you out wheeling? The sensor code indicates a possiable broken wire, which you will need to repair. The broken wire could be in the body harness (mouse got hungry?).
Or just buy the sensor, make sure you have a deep socket or a wrench with some leverage & remove it. Try not to strip out the threads in the exhaust pipe. Might be easier to cut the wire at the sensor & put a socket over it.