Every human being has his or her own mix of the three types. As an individual you possess unique characteristics, physical features and talents that indicate a certain distribution of the types. It is rare that you belong to just one constitution type. Often there is a mixed type, in which one type can dominate. If one type clearly dominates the other two, for example if we see a lot of deer-type but only a little tiger-type and elephant-type, then you have a predominantly deer-type constitution.
Another example; if you are as much tiger type (pitta) as elephant type (kapha) and only a little deer type (vata), then you are a tiger-elephant-type (pitta-kapha).
Nutritionally, this means that you benefit from a diet that belongs to your constitution type. In practice this translates into the development of a diet that suits your constitution.