There are a lot of different measures of HRV, and I'm not sure what one the watch might be using. Some are considered more reliable than others and give a better idea of what is going on. Essentially the nerve that slows down HR (the vagus) works in waves with your breathing (when resting anyway) to cause a slight speeding and slowing known as respiratory sinus arrhythmia (which is normal, not like a bad arrythmia!). The more this happens, the better generally. More vagal activity at rest is protective for the heart, and HRV is a marker of that activity... Anyway, HRV is quite a tricky thing to measure as is effected by a lot of things, including exercise, time of day, menstrual cycle, stress, noise, caffeine, food, hot/cold, posture etc. etc. Without knowing the time period over which it calculates HRV, and what you were doing in that time, it's difficult to draw any conclusions. There's also not really a typical HRV figure you can quote as 'good' or 'bad' really like you can with say resting HR, as they are very individual. What is more useful is in tracking changes over time, and seeing how responds to different things, and might have some prognostic value then in reflecting lifestyle/health changes that could be effecting you.
So in short, I wouldn't say your current reading was very useful in it's own. Chances are if unfit and stressed, then is going to be lower though. It's not going to form the basis of any kind of diagnosis or investigation though, and if you went to the GP and said your HRV was low, they'd probably just look at you a bit strangely.