Do you have any working experience prior or are you just getting out of college?
If they ask you anything like, "tell me about yourself" make sure to respond about professional situations! They're not necessarily asking to find out about your personality, but more about how you handle yourself professionally. I usually say "I've been in customer service for over eight years, and I love being able to work with a team to solve problems and assist customers. I think the best reward I can get is a "thank you!" From a customer I have helped. I always look to get the customer the best resolution, even if it means inconvenience to myself." That way, I'm still talking about me, but in a business sense!
If they ask about your strengths, don't just say something like "I'm great with numbers". Make sure to keep it specific to the job, and elaborate a little but not too much. "I find that I excel best when mathematics are involved. It gives me a great sense of satisfaction in my job to know I'm contributing to xyz by utilizing the skills I went to college for" or you could say something like, "I think my biggest strength is being a great leader. I've always naturally found myself leading others, whether in trends or in group projects. I really enjoy when others come to me with problems that need solving." (That's the one I use 😉)
When asked about weaknesses, don't be "honest". What I mean by that is don't say "I'm bad at remembering to respond to inquiries." Say something instead like: when you first started college, you struggled a lot planning out classes, due dates, and free time. You found you dedicated a lot of time to things that didn't necessarily need it, such as writing essays and big projects too far in advance, so you would have to rush to catch up on smaller projects. These days, you find yourself reminding yourself to slow down a lot more, and ensure that you've gone over everything with a fine tooth comb. Be honest about a struggle, but say what you are actively doing to overcome it!
They will also probably ask why you want to work for Pfizer. My answer usually is "because your employees rate your company so high on benefits, satisfaction in their jobs, and overall view of the company." (I never apply to jobs anymore where that isn't true) and thankfully, that's true for Pfizer too!
Let us know how it goes!!! From everything I've seen they're an amazing company to work for. If you've made it to the third round, that means they really like you! Best of luck to you!!!!