This summary is not the rule. The rule text controls.
Sometimes evidence in a trial is allowed for one reason but not another. For example, a statement might be okay to use against one person on trial but not against someone else charged in the same case. Or a piece of evidence might be allowed to prove one point but not another.
When this happens, a party can ask the judge to limit how the jury uses that evidence. If someone makes this request at the right time, the judge must tell the jury exactly how they are allowed to use the evidence and warn them not to use it in ways that are not allowed.
This rule protects people from being unfairly judged based on evidence that was never meant to apply to them. It also makes sure the jury understands the difference between evidence that applies broadly and evidence that only applies in a limited way. Without this kind of instruction, jurors might wrongly assume all evidence applies equally to every person or issue in the case.