From

Shows the dimension value that serves as a trigger for the target dimension to be displayed. For example, in a wine store catalog, you might set up a precedence rule whereby the Winery dimension is not displayed until the Region dimension value has been selected. In this example, the Region dimension value would be displayed in the From column.

To

Shows the dimension that serves as the target for the trigger dimension value. Extending the example above, the Winery dimension would be the target.