Okay, so have you ever seen a picture where there are rows and columns of small pictures all in one big picture? That big picture is like a hard drive, and each small picture is a part of the hard drive where information is stored.
Zone bit recording is when you organize those rows and columns of small pictures into groups. Each group has a different amount of small pictures in it, so they can store different amounts of information.
This way, information is stored more efficiently on the hard drive, because instead of having just one size for all the parts, you have different sizes that can hold different amounts of information. It's like having different sized containers for different things in your room, instead of just one size for everything.