Publishing articles open access normally means authors must pay a fee to the journal. However, thanks to ‘read and publish’ or ‘transformative’ agreements between the university and some publishers, University of Cambridge researchers will be able to publish open access with any journals covered by such agreements.
There are some conditions. The articles need to be primary research, or review articles. In addition, the corresponding author must have an affiliation with Cambridge (in other words, the agreements would not cover articles in which one of the co-authors was from the University of Cambridge, but the corresponding author was not).
You can read about these agreements in more detail, as well as view a list of the publishing companies currently signed up for such agreements, on the University of Cambridge Open Access website.