Following is C like pseudo code of a function that takes a Queue as an argument, and uses a stack S to do processing.
void fun(Queue *Q)
{
    Stack S;  // Say it creates an empty stack S
 
    // Run while Q is not empty
    while (!isEmpty(Q))
    {
        // deQueue an item from Q and push the dequeued item to S
              push(&S, deQueue(Q));
   }
 
    // Run while Stack S is not empty
    while (!isEmpty(&S))
    {
      // Pop an item from S and enqueue the poppped item to Q
      enQueue(Q, pop(&S));
    }
}

What does the above function do in general?