Ah wait, it's a riddle!
By forces, he means the two sides of the Force, dark and light. They come together at full strength when Anakin brings balance to the Force, so they are perfectly balanced at full strength within himself when he saves Luke and destroys the Emperor in Return of the Jedi. This is also when the Forces of the Empire and the Forces of the Rebellion come together at full strength. So the number you're searching for, bruninho, is 6.