Orwell's purpose in "Politics and the English Language" is to demonstrate the connection between sloppy use of language and corrupt politics and to give advice about how to avoid such bad writing.
Orwell divides his essay into two parts. In the first part, he provides specific examples of bad writing and details what exactly it is that makes them so. Orwell singles out the use of meaningless metaphors and elaborate diction and argues that such writing indicates a lack of clear thinking or a kind of intellectual laziness.
The second part argues that almost all political writing is bad in this way. Poor writing clouds meaning, making it seem like the writer is saying something when there is in fact no meaning to the words. In this way, poor writing fosters poor political thinking and is a real danger to society.
Orwell also illustrates how bad writing can function as a cover for any political atrocity. Rather than concretely describing the actions taken by a government, excessively Latinized language "falls upon the facts like soft snow, blurring the outline and covering up all the detail."
Orwell concludes by giving some specific advice on how to improve written English. His advice is to always seek to simplify one's language and to always be concrete. His hope is that if we can begin to use language to clearly express ideas, the quality of our political life will improve.