From the Home tab in Power BI Desktop, you click Enter Data and create a table named Sales that contains the following data. You add Region and Sales to visualization and the visualization displays…

The Data Category of Region helps with geographical mapping but does not cause aggregation or reduction in row count in this context.

When a categorical field like 'Region' is placed on an axis in a Power BI visual, the data is inherently grouped by the distinct values of that field. If there are only four unique regions among the six source rows, this default grouping behavior causes the visualization to display four rows, each representing a distinct region.

The Default Summarization on Sales determines how the numeric 'Sales' values are aggregated (e.g., summed) within each group, but it is not the primary cause of the reduction in the number of rows from six to four, which is driven by the grouping of the 'Region' field.

The Data Category of Sales (numeric) is irrelevant to how rows are grouped or reduced in a visual.