The initial application online is followed by a series of online questionnaires. If these are passed, then your CV and covering letter are reviewed -- if they like what they see, then you are progressed through to sit a Problem Solving / Reasoning Test. If you pass this, then you progress on to interviews -- 2 to 3 in total, with 1-2 people in the room each time.
The interviews focus around the competencies that P&G calls "Success Drivers" -- things like leadership, teamworking, problem-solving, decision-making, innovation, adaptability, etc. They ask that you answer each interview question by giving an example from the past of when you have shown the needed behaviour. They request that you use the CAR format: Context (give a little background, set the scene); Action (talk about what YOU did, distinguish vs team) and Result (what did you deliver in the end?).
On the whole not a difficult interview process if you have plenty of experience, particularly in extra-curricular university activities such as sports and societies. If you are light on leadership experience you will find the interview very difficult to pass.