This rule determines if there is defined style
text-indent with the value so that the element is being positioned out of the viewport.
The technique e.g.
text-indent: -10000px is still being used to hide the content visually. However, the downside of that technique is that the screen reader focus follows that and it gets out of the visible area.
The rule passes when there is no defined style
text-indent that hides the content outside of viewport.
Hot to fix it
Use a technique that hides the content visually, but does not move the element outside of the visible viewport. See example from Bootstrap.
Accessibility, Best Practices