This summary is not the rule. The rule text controls.
When a child is being held (detained) before their case is fully resolved, a judge must hold a hearing to decide if that detention is really necessary. At this hearing, the judge can look at any evidence that helps answer that question, even if it wouldn't normally be allowed in other kinds of court hearings.
Sometimes the child's parents can't be found, even after someone makes a real effort to reach them. If that happens, the hearing can still move forward without them. But the court has to protect the child's interests by appointing a guardian ad litem, which is a person assigned to speak up for the child and look out for their well-being during the hearing.
This rule exists so that a child isn't kept waiting in detention just because their parents are unreachable. It balances two needs: making sure detention decisions happen quickly, and making sure someone is still looking out for the child even if mom or dad isn't there.