It means you can control it, but you don't neceserelly have to be aware of that you're dreaming. It's funny actually - you can do some things over, and over and over...lika a movie track! )
A lucid dream refers to a time when you are conscious of your dream. Lucid is defined as: Clear or transparent. So your mind is clear and you can see what you are dreaming. Often Lucid dreams are vivid and realistic. You may or may not be able to manipulate your dream, and you may or may not remember the experience.