standard deviation tells you how close the various data points are to the mean - a high standard deviation means the data is spread out, a low standard deviation means most the data is fairly close to the mean.
So if all the data is the same value, the standard deviation is zero.
1 standard deviation from the mean in either direction accounts for around 68 percent of data. 95% of data is within 2 standard deviations of the mean and 3 standard deviations accounts for 99% of data.
i.e 68% of your data is between -5.2 and 62.4