What is an example of a Global Bury rule?

To bury products in search results, drag the Boost slider to the left to select a negative boost value:

This rule states that products that have a Sale Price equal to/less than 20, should be pushed further down results. You can preview some of these products that would satisfy this condition by clicking on the "Calculate & Show Matches Preview" button:

By testing in the Preview section, you can see that the first item above is showing a negative boost value in search:

Hovering over the highlighted Boost value will display a popup, where you can click on the View Details button to see how this Boost value is being calculated:

Here you will find the Ranking/Sorting Rules that apply to the item: