This summary is not the rule. The rule text controls.
Here's how evidence gets presented during a trial. The side that has to prove their case goes first and presents their evidence. Then the other side gets their turn to present evidence too.
After both sides have gone through their main evidence, they can only bring up new evidence to rebut, or counter, what the other side said. The judge normally won't let either side go back and add more to their original case at this point. However, if there's a good reason, the judge can allow it.
This order keeps trials organized and fair. It gives each side a clear turn to make their case, then a chance to respond to what the other side argued. The judge has some flexibility to bend this order if it makes sense for the case, but the standard setup keeps things moving in a predictable way.