Super confused about swapHead method in lesson

The code for swapHead is as follows

public String swapHead(String characterName) {
    String originalCharacterName = this.characterName;
    this.characterName = characterName;
    return originalCharacterName
  }

characterName is what is passed in. In this case "Darth Vader"

String originalCharacterName = this.characterName; . This stores the current name in originalCharacterName. In this case "Yoda"

this.characterName = characterName; This sets the current name to the name passed in. The current name is now "Darth Vader"

return originalCharacterName; The return value is the stored original name. In the case "Yoda"