This summary is not the rule. The rule text controls.
Here's a plain English summary of this rule:
When a jury gets sworn in for a trial, the court clerk has to handle the ballots (the slips with juror names on them) in a specific way. The ballots for people who were absent or excused from serving go right back into the box immediately. This keeps the pool ready for future jury selections.
The ballots for jurors who actually got sworn in and will serve on the case get set aside separately. They stay out of the box while that jury is doing its job. Once the jury finishes its work and gets discharged, those ballots go back into the box too.
This rule just makes sure the jury selection process stays organized and fair. It keeps track of who has already served or been excused, so the same names get properly recycled back into the pool for future cases once their service is done.