This summary is not the rule. The rule text controls.
Sometimes evidence can be used for one reason but not another, or against one person in a case but not someone else. When that happens, this rule says the judge must tell the jury exactly how they can and cannot use that evidence, but only if someone asks for this instruction at the right time.
For example, imagine two people are on trial together and a witness says something that proves one defendant's guilt but has nothing to do with the other defendant. The jury can't just use that statement against both people equally. If a lawyer asks the judge to step in, the judge has to explain to the jury that the evidence only counts against one defendant, not the other.
This rule protects people from being unfairly judged based on evidence that doesn't actually apply to them. It puts the responsibility on the lawyers to speak up and ask for these limits. If nobody asks, the judge does not have to give this special instruction on their own.
