the only purpose of descriptions is to awaken you to a new level of possibilities of differentiation.
once your mind is equipped with those, it needs to apply them to real people and see how they occur in reality.
the more simple your basic differentiations are, the more useful they will be for pattern scanning.
you need more differentiations than just 8 functions or in a sense actually less, it's more useful to work with 4 functions (FTNS) and two modulations: objectivity (extroversion) and subjectivity (introversion). or to begin with, work with perception, judgement, objectivity, subjectivity.
it's extremely helpful if you are also able to recognize/differentiate stages of development (ken wilber, spiral dynamics) or else you will confuse those with functions, especially subjectivity/objectivity will be confused with stages.
next you go looking at neurotic people on message boards, for a couple of years. who spill their guts out and argue endlessly. arguments are most useful to discover where people are opposed and where misunderstandings come from. this will teach you to see the functions (and stages) in reality.
it's not your job to describe them to someone based on what you have read and and appear smart when you have no idea what you are talking about. typology has enough copy cats. if you can't see functions in reality, you don't know them.
i believe the ability to see functions requires a feature called vision logic and this is something that people may grow at a certain age, somewhere in their twenties.
actually vision logic sees all sorts of differentiations of human interiority. the ability to sort them out, name them and decide which one's are relevant to typology doesn't fall from the sky.
for instance saying that static objects are sensation and dynamic objects are intuitive is like a hypothesis that needs to be tested forever, but the ability to differentiate between such aspects is the basic tool. it's all you have to work with, all a description has to make you discover in your self.
typology is a skill, not a knowledge base.
vision logic is not Ti or Ne or Ni or any particular function, it is something larger, that emerges from many functions working together while being differentiated from each other. you become aware of how everything in reality highlights a different part of yourself and you can keep track of it. understanding functions, that you make little use of yet, remains difficult.