Hello everyone, what does this type of temperature graph mean, also what does the block dataset represent ?
Thanks 
What you are seeing is a quartile chart. (Note the QuartileChartView label in the upper right.) When you ran the PlotDataOverTime filter, at each time point (x axis) you are considering all of the values of your data set at that time. This chart is showing a statistical summary of the data at each time step.
The dark line is showing the average value at each time step. The somewhat less darker region is showing the range where 50% of the values lie. The lighter region around that is showing the total envelope of all values. So, the light region above the darker region is showing the range of the upper 25% of values and the small light region below the darker region is showing the range of the lower 25% of values.