Looks like the description is blank. That's unfortunate. It means the person who built the DS didn't actually tell you what it means. Monitoring_Status is not a DS built by LM, so it would have been built by someone in your portal or downloaded from the exchange from someone else who built it and posted it.
However, we can probably derive what it means. Given that the DS name is "Monitoring Status" and the datapoint is "MonitoringStatus", it probably attempts to tell whether or not the device is being monitored. Also, since the threshold is "> 0 0" it probably returns a 0 when things are bad. My guess is that this attempts to tell you whether or not the device is being monitored and returns a 1 if it is and a 0 if it isn't.
We could probably confirm this by looking at the DS definition itself. Is it scripted? If so, would you mind posting the script here? Make sure any passwords or keys are replaced with dummy values.