This summary is not the rule. The rule text controls.
If you win a money judgment in a civil case, and the other side appeals but loses, you still get interest on that money. This rule says the interest counts from the date the trial court first entered the judgment, not from the date the appeals court makes its final decision.
This matters because appeals can take months or even years. Without this rule, someone could lose money by having to wait through a long appeal before earning any interest. Instead, the law treats the interest as if it had been building up the whole time, starting from the original judgment date in the trial court.
There is an exception if some other law specifically says interest should be handled differently. But in most cases, this rule protects the person who won the judgment by making sure they get full interest for the entire time the case was tied up in appeals.