Imagine you have a big glass of milk and a small glass of milk. If you pour all the milk from the big glass into the small glass, the milk will fill up the small glass completely and there won't be any space left. This means that the small glass has a distribution volume of one big glass.
Now, let's say you have some medicine in your body. The distribution volume is like the size of your body compared to the amount of medicine in it. If you have a lot of medicine in your body, but it's spread out evenly throughout your body, then your distribution volume is high. This means that the medicine is very well distributed throughout your body and is available to go everywhere it needs to go to do its job.
On the other hand, if you have a small amount of medicine in your body, but it's all concentrated in one area, like your stomach, then your distribution volume is low. This means that the medicine is only available in one small area of your body and may not be able to go where it needs to go to do its job effectively.
So, in simple terms, distribution volume is like the "size" of your body compared to the amount of medicine or other substance in it. A high distribution volume means the substance is well distributed throughout your body, while a low distribution volume means it's concentrated in one area.