Literal translation
it's the fifth wheel of the cart
Meaning
he's a fifth wheel, of no real use
Explanation
The image rests on the simple mechanical fact that a cart only rolls on four wheels: a fifth wheel therefore serves no purpose, it only gets in the way without fulfilling any useful function. The expression thus designates a superfluous person within a group, someone entrusted with nothing and whose presence changes nothing in how things proceed, whether ignored out of indifference or kept away from decisions. The word càrri means cart or wagon, a wheeled vehicle drawn by an animal and familiar in rural Provence, and rodo means wheel, both very concrete terms that ground the image in the everyday farming life of the past. The expression matches its French equivalent almost word for word, testifying to a shared stock of imagery built around the wheeled vehicle. It is used in a familiar register, often with a touch of bitterness from someone who feels sidelined that way, or with mild irony from someone simply observing the scene.