"Grouping" icon will be displayed on the Tool Palette only when the data model of the output destination component is XML type and will not be displayed when it is table model type.
When you prefer to output the result of grouping the data of the table model type such as CSV and RDB, using the Mapper continuously as given below, group the data in the 1st Mapper as the temporary XML data and is feasible to display the XML type to the table model type component in the 2nd Mapper.
Input data → Mapper:A → Mapper:B → Output data
Refer to "Grouping" in the help for the details of "Grouping" icon.