This summary is not the rule. The rule text controls.
Here's what this rule means if you're trying to get real property (land or buildings) back through a lawsuit.
Sometimes a person files a lawsuit because they had a right to the property when they started the case. But by the time the case goes to trial, that right has run out. Maybe a lease ended, a time limit passed, or some other change happened during the lawsuit. This rule says the judge and jury still have to base their decision on the actual facts, not just on what was true when the lawsuit began.
Even if the plaintiff's right to the property ended before trial, they can still win money for the time the other person wrongfully held onto the property. So the case isn't thrown out just because the right expired. The court will look at the whole timeline and decide what's fair based on how things actually played out, including compensating the plaintiff for the period they were kept out of their property.