It seems like “adulthood” can be replaced with “adult”. But is “adulthood” used often in real conversation?

What is the meaning of "take" here?

"Take" in this context is used to identify or give an example of something. It often either follows "for example", or is placed right before the phrase "for example". Ex: Dogs are great pets. Take my dog for example, he is very well-behaved. Ex: Not all jobs that require a degree pay a good salary. Take teachers for example, they make barely anything.

What is the meaning of "you are" at the end of the sentence?

"You are" here is a part of the expression "as you are", which means someone's appearance or personality without any cover ups or changes to who they are as themselves when they are being themselves. Ex: You don't have to wear makeup. You look pretty as you are.

What's the difference between "nonfiction" and "fiction"?

That is an excellent question. Typically when we use the word "fiction” it is to refer to things that are created completely using our imagination. In the case of books, it means that the events, characters, everything is completely the idea of the person writing the book. Within "fiction" there will be lots of "genres" or types, just like with a film. It might be mysteries, science fiction, romance, etc. “Nonfiction” is used to refers to things that are based on fact, meaning that the contents of a book, for example, really happened or the people really existed. Just like "fiction" "non-fiction" also has different genres such as business, cooking, travel, etc. You will often hear people say that something is a "work of fiction" when they talk about a person lying. Ex: If you're looking for a cookbook it will be in the non-fiction section. Ex: I love fantasy books because I prefer fiction over non-fiction.

What is the difference between "make" and "maketh"?

It's an old form of "makes". The -t(h) ending and the -s ending had been in competition in English verbs for centuries, until finally the -s won in modern English.

I thought "kind" means "good" like "I'm a kind person", but what's it mean here?

Here "kind of" means "to an extent." Some other phrases you could use are "rather," "sort of," or "quite." Ex: The movie was kind of sad. Ex: The party was kind of a way to celebrate Jamie's graduation, but it was also just for fun.