‘Knocking Back’ dough refers to the process of working the dough after the first proving. At this stage the CO2 gas produced by the yeast during fermentation is not always distributed evenly, and by working the dough the larger bubbles are removed. By this stage in the bread-making process the yeast is working well, and the second proving will take much less time than the first.
You will also discover that the gluten is now more fully developed. From what I have read whilst researching no-knead bread, the proteins in gluten form a network of strands that are helped by the presence of salt and time.
So, what do you need to do? Basically reduce the volume of the dough by pressing the fist into the dough ball, then removing the dough from the bowl to a lightly floured or oiled surface, and kneading gently for a minute or two. The decision to used flour or oil is driven by the consistency of the dough. If you find it wet or sticky at this stage, you can use flour. On the other hand if you wish to not dry the dough out because it has a good consistency, a little oil spread on the work surface will go a long way to preserving that consistency.
At this stage, the dough is ready for shaping.