This summary is not the rule. The rule text controls.
Once the jury leaves to start deciding a case, they sometimes have questions or want more information. This rule says the judge can't just answer those questions privately or send information back to the jury room. Everything has to happen out in the open, in the courtroom.
The defendant has to be there when the judge responds, unless the trial is happening without them (which can occur if they've run off during the trial). The whole jury needs to be present too, not just the person who asked the question. This keeps one juror from getting special information that the others don't hear.
The lawyers for both sides also get to be part of this process. Either they need to be in the courtroom when the judge answers, or they need to be given fair notice beforehand so they have a chance to be there. This rule exists to make sure nothing happens behind closed doors that could unfairly affect the case. Both sides deserve to know what the jury is asking and how the judge responds.