Adds a space and a number in parenthesis to the name of an instantiated or duplicated GameObject ("Prefab (1)").
When a GameObject is duplicated or instantiated, Unity copies the original GameObject's name and adds a space and a successive number in parenthesis to it, for example, "Prefab (1)".
Additional resources: EditorSettings.gameObjectNamingScheme, EditorSettings.gameObjectNamingDigits.