Basically the same as your fermenting bucket, but you don t need a hole in the lid, or an airlock. Again, a spigot is helpful, but keep it clean. You transfer the beer from the fermenting vessel into the bottling bucket. You then transfer it from the bottling bucket into the bottles. Each time you rack between vessels you re leaving a layer of yucky-tasting yeast sediment at the bottom, keeping it from spending too much time with your beer.
Hydrometers look like big thermometers with weighted bottoms.
You drop it into your beer and it measures the density of the liquid in relation to water. In brewing, it tells you how much fermentable sugar is in the beer. You take it at the beginning to get the potential alcohol volume of your finished beer. You also take it before bottling to see how much of the fermentable sugars were actually fermented. Then you can be sure that fermentation is actually done, and your beer is ready to bottle.