If you wanted to better understand trees, you might go into the forest and observe certain characteristics that always that are always present and grouped together and label them a pine tree. Another set of characteristics you might call an oak tree, and a third set could be an elm tree. With this typology whenever you went into any forest, you would be able to differentiate one tree from another. This typing of trees make the forest more understandable. A typology always simplifies and some subtle details are lost but there is an increase in general understanding.
Typologies facilitate a gain in the general understanding by making clear what commonalties exist.
Typologies of personality help us understand human behavior. They also simplify, but clarity is gained and uniqueness is not lost. One pine tree or one person always continues to differ from every other and thus remains unique. Applied to people a typology takes the variety of human characteristics and puts them into a limited number of categories as an aid to understanding. The Jungian model of personality is a typology.