There are real tangible things, like a rock or a tree, perhaps a house, or a horse.
Then there are the myths that humans created, like countries, laws, money, a limited company, and so on. These things are of the mind and only exist as long as we all collectively keep the myth going by believing and abiding by them.
If we are not content with the world and the myths that control us, then we can stop following them or create some new myths.
But be certain, myths are what has been controlling humans for 10’s of thousands of years.