Oxbridge are the most prestigious unis in Britain. They are well known around the world and have a rich history behind them.
Everyone no matter where they are, have heard of them.
They are know for having high standards with rigorous exams, an highly competitive environment, societies which only attract the best, students who go on to be future world leading lawyers, doctors, politicians, scientists and an admission process which only selects the best of applicants.
A degree from there is seen as a holy grail and you’ll get offers from just about anywhere just by having one of them.