The Academic reading module of IELTS consists of three reading passages and 40 questions:
You will have to read approximately 2,500 words in total.
The passages deal with a range of academic subjects: one may be about ancient history, another about astronomy, another about advertising techniques, and so on.
Each passage in IELTS reading is followed by 11 to 15 questions. You can read and answer questions at the same time. The questions could be multiple choice, matching, true/false/not given, sentence completion or summary completion tasks.
The reading module of IELTS lasts one hour. You should be able to skim-read approximately 170 words per minute and spend no more than 15 minutes in total reading the three passages. That will leave you around one minute to attempt each question plus a little extra time for checking.