When I was at high school, my teacher said that: "How + be + Subject? is only used for asking someone's heath" and" What + do/does + Subject + do?" is only used for asking someone's job.
That's why I felt confused when I made questions for these sentences. However I still used those structures to make questions. I don't know if it's right or wrong :/
1. It's a huge, blue and fast car.
=> How is the car?
2. He gives her the keys and says: OK!
=> What does he do?
Your statements would not be natural ways to say things in English.
To ask about a description of a car, we would more likely say something like ¨What kind of car is it?¨ or ¨What is the car like?¨ Your teacher is right that ¨How is ____________?¨ is used to ask about health or proper functioning. If someone asked me ¨How is the car?¨ I would think they were asking me if it was working properly or perhaps if it had been damaged in a wreck, not for a description of it.
To ask about what someone is in the process of doing right now, we would say ¨What is he doing?¨. ¨What does he do?¨ is used mostly to describe occupations or, at the least, how someone habitually spends their time on a daily basis.