I want to create a boxplot for a GIS data shown :- 
But when I try to create a boxplot for the data I am unable to see the layer being added in Layers/Table as shown: 
Why does this happen? And how can these be solved??
Your input is a float raster; in the help file here it clearly states the sources of data that can be used to construct the various charts ArcMap can create. Float rasters don't have attribute tables hence you cannot build any sort of chart from it.
You could try multiplying up your raster by say 1 million to move the decimal point, then convert the raster to integer using the int tool and graph that?