When after the selection of a data set in a worksheet the immediately shown measures of the data are not enough then descriptive statistics app, shown in Fig 1, is very useful to summarize the given data set using more measures such as mean, median, variance, range and mode...
Figure 1: Descriptive Statistics App (3 measures are selected)
Once the data is selected from a worksheet, either all or individual measures of the data can be selected. If more than 1 column of data is selected, either the whole data set or each individual column can be analyzed separately.
For the simple data set shown in Fig 1, below is a report showing the difference of selecting and not selecting the "Treat columns separately" option: