Bread and yeast products usually always get two times to rise. After the first rise, you will actually punch all of the gas out of the dough, but this is the only time you'll do that. This is to get rid of any large gas bubbles that might have been created and the yeast will be strong enough for a second rise. It's on this second rise that the bubbles will appear more even and creating a better texture. After the second rise is when you'll eventually transfer your bread to the oven. The dough should look almost like it would be if it was baked. It should be fairly firm and show no bubbles on the outer crust. That happens when the dough is left too long to rise and the gas begins to escape from the inside. This is called "over-proofing". If you were to bake a loaf like this, it would be flatter and more dense because the gases escaped before you put it in the oven. The key is to keep those gas bubbles intact and inside the dough to end up with a light airy texture.