All postgrad students, both MSc and PhD students, must submit a written report six months after their enrolment. This is a departmental requirement rather than a University requirement: the aim is to ensure that students start writing about their research at a reasonably early point in their course.
The six-month report could be a literature review, or a research proposal; its content is something you need to decide jointly with your supervisors.
The postgrad coordinator will email you around a month before it's due; at that point you should discuss with your supervisors what to put in the report, write the report, and when your supervisors are happy with it, send it to the postgrad coordinator. It will then be posted on the department's postgrad students page. The report will only be viewable locally within the University, and it doesn't have to be of 'publication' standard, but it should still be thought of as a document for public consumption.
A note about timing: for PhD students, the six-month report is due at the same time as the first self-review report (around 7 months rather than 6). For more information see the progress meetings page.
If you have any questions about the report or its content, please contact the postgrad coordinator.