Mother Courage's covered wagon is on the stage in nearly every scene. As the different characters—Eilif, Swiss Cheese, the chaplain, the cook, Kattrin, and last but not least, Mother Courage herself—haul the wagon around Europe, it becomes both a literal and a symbolic burden they all have to bear.
What this burden represents is open to question. We can, for example, think of it as the burden of survival itself. Consider the final scene, when Mother Courage hitches herself to her wagon and heads back to business:
MOTHER COURAGE harnessing herself to the cart: Hope I can pull the cart all right by meself. Be all right, nowt much inside it. Got to get back in business again.
Another regiment with its fifes and drums marches past in the background.
MOTHER COURAGE tugging the cart: Take me along! […] (XII, 42-49)
When Mother Courage has to start hauling her wagon all alone, it's hard not to think that this burden will be too much for her. She expresses some doubts about it herself. Here, we might say that the difficulty with which she drags her wagon stands for the difficulty she will have carrying on after the death of her children. If making it like this is an example of her "courage," then it is of the kind that Mother Courage earlier attributes to "poor folk," who have to have courage just to keep going, "'cause there's no hope for them" (VI, 148).