This summary is not the rule. The rule text controls.
This rule deals with a situation where a defendant is caught in the middle of a dispute between two other people who both claim they're owed the same money or property. Instead of getting stuck defending against both claims, the defendant can ask the court to bring in the other claimant and let them fight it out.
Here's how it works. If the defendant points to a third person who also claims the same money or property, that third person can step into the case and take the defendant's place. Once this happens, the original defendant can be let go from the case entirely, as long as they follow the steps laid out in rule 1.253 (which usually means handing over the disputed money or property to the court).
In simple terms, this protects someone who owes money or holds property but isn't sure who should actually get it. Instead of that person getting sued twice or facing conflicting demands, they can step aside and let the real claimants settle the matter between themselves in court.