All creatures are described with the same characteristics, which will allow comparisons to be made. Each characteristic defines some aspect of the creature or character - and, taken together, the characteristics will help to decide what they are good at and what they are not so good at.
All creatures are described using this set of characteristics. In certain cases, though, a creature may have a characteristic score of 0. This means it has no ability to perform tasks associated with that characteristic. A creature with no hands, for example, would probably have a Dex of 0.