Blended Axis is used to blend two measures that share an axis when they have the same scale.
Scenario: Show Min and Max profit in the same pane and have a unified axis for both, so that it is quicker and easier to interpret the chart.
First, create a visualization that shows sales over time. Next, see profit along with sales over the same time. Here, you get two visualizations, one for sales over time and the other for-profit over time.
To see a visualization that has a blended axis for sales over time and profit over time, we bring in Measure Values and select the properties that we want to keep (Sales and Profit), removing all of the rest. You can now see profit and sales over one blended axis.