The AXIS COLUMNS keyword defines an axis for the columns of a visual shape for visual calculations.
Find more in Introducing VISUAL SHAPE for visual calculations in Power BI.
The following example shows an example of a visual shape definition in a DAX query.

    TABLE '__DS0VisualCalcs' = __DS0VisualCalcsInput
        WITH VISUAL SHAPE
        AXIS ROWS
            GROUP [Brand]
                TOTAL [IsGrandTotalRowTotal]
            GROUP
                [Category],
                [Category_Code]
                TOTAL [IsDM1Total]
            GROUP [Color]
                TOTAL [IsDM3Total]
            ORDER BY
                [Brand] ASC,
                [Category_Code] ASC,
                [Category] ASC,
                [Color] ASC
        AXIS COLUMNS
            GROUP [Year]
                TOTAL [IsGrandTotalColumnTotal]
            GROUP
                [Month],
                [Month_Number]
                TOTAL [IsDM6Total]
            ORDER BY
                [Year] ASC,
                [Month_Number] ASC,
                [Month] ASC
        DENSIFY "IsDensifiedRow"