What it does: Summarizes the data by one or more column values, and either gives a count, sum or average. Works similarly to a pivot table.
How to use it: Pick the column you want to count, sum, or average. Then pick one or more columns to use to cut the data (can be the same column). If you'd like to group by a time period, select the "Date Grouping" option.
Tip: You may want to use a "Pivot" object to make the data more legible.