This summary is not the rule. The rule text controls.
Both sides in a court case can agree to use a smaller jury than usual. Normally a jury has six people, but the parties can agree ahead of time to have fewer jurors decide the case. This agreement has to happen before the jury is picked.
The parties can also agree that they don't need every juror to agree on the verdict. Instead, they can decide that if a certain number of jurors agree (a majority), that's good enough to count as the jury's official verdict. This kind of agreement has to be made before the jury announces its decision.
Basically, this rule gives people involved in a lawsuit some flexibility. They don't have to stick with the standard six person jury or require every single juror to agree, as long as both sides work it out and agree on the details in advance.
