This summary is not the rule. The rule text controls.
When you appeal a case in Missouri, the appeals court has several options for how to handle it. The court can order a new trial, order a new trial on just part of the case, or reverse or uphold the trial court's decision, either fully or in part. The court can also enter the judgment that it believes should have been made in the first place.
The main goal of this rule is to bring cases to a final end whenever possible. Instead of sending a case back to the trial court over and over, the appeals court is expected to settle the matter once and for all, unless doing so would be unfair to one of the sides. This saves time and money for everyone involved and helps avoid cases dragging on for years.
In practice, this means that if you win your appeal, the appeals court will usually try to fix the problem itself rather than just sending your case back for another trial. Only when fairness truly requires more proceedings will the court send the case back down for further action.