If you don’t look carefully, you might miss that this is actually a required prompt from Oxford - even though it is worded almost exactly like an optional question.

Of course, if you have areas of concern in your profile that you might typically address in an optional essay (like choice of recommenders or poor academic performance), this is the right space to do so. However, this is also the perfect place to round up your candidacy. Think carefully about what all the admission committee has learned about you from your resume, recommendations and application questions and then weigh it against the picture you would like to present. Then, use this space to shed light on the parts of your profile that have not yet been highlighted. It could be a professional achievement that you are particularly proud of or an impactful personal event or an extra-curricular activity that has been significant in your life. The key here is to provide as much positive information as possible to nudge you into the direction of an admit.