This pane shows you the SQL code as it is developed. You can directly edit the code, and the fields are automatically updated in the Query Editor user interface.
You will notice that this SQL looks a little different from the SQL you normally write. This SQL is fully formed, meaning that all tables are prefixed with owner name, all strings are enclosed in quotation marks, and so on. This extra formatting is not normally necessary, but it ensures that the SQL works in all situations.