What does writing in an impersonal style mean?
When you write your essay, you need to use an impersonal style, as you are writing objectively about impersonal topics.
Academic writing is used for discussing facts and ideas about the world. It does not give personal details. The writer does not know the reader, and so does not address him or her as a friend.
Academic writing style, therefore, is not informal and personal. It is formal and impersonal. To write in a more formal, impersonal style we need to avoid using I, you and we.