This summary is not the rule. The rule text controls.
Here's a plain English summary of this rule.
This rule deals with situations where someone wants to use a copy or description of a document instead of the original, and there's a dispute about whether that's allowed. Normally, the judge decides whether the conditions are met to let in this kind of substitute evidence. For example, if someone claims the original document was lost or destroyed, the judge usually decides if that's true enough to allow a copy to be used instead.
But there are three specific situations where the jury, not the judge, gets to make the final call. First, if there's a real dispute about whether the original document ever existed at all. Second, if there's a question about whether a document brought to court is actually the genuine original. Third, if people disagree about whether a copy or description actually matches what the original document said.
In these three situations, the judge still lets the evidence in initially, but the jury decides how much to believe it. This matters because it means the other side gets to argue directly to the jury that a document is fake, doesn't exist, or was copied wrong. The jury then weighs that argument along with everything else when they decide the case.