This summary is not the rule. The rule text controls.
Here's what this rule means. In some cases, you don't have an automatic right to a jury trial. The judge normally decides these cases alone. But this rule gives the judge some flexibility.
First, the judge can choose to bring in a jury just for advice, even though the law doesn't require it. This is called an advisory jury. The jury listens to the case and gives its opinion, but the judge still makes the final decision. The judge doesn't have to follow what the jury says.
Second, if everyone involved in the case agrees, they can ask for a real jury trial instead. If all sides consent and this is officially noted in the court record, the jury's decision counts just like it would in a case where a jury trial was required by law. In other words, the judge must accept the jury's verdict as final, the same as in any standard jury trial.
This rule basically gives judges and parties more options. It allows extra input from a jury even in cases that normally wouldn't involve one, and it lets everyone agree to make that jury's decision binding if they want to.