I can see your dilemma. It is not easy to answer a question that is so broad. Moreover, you want to say substantive things about yourself without appearing too proud. In light of this, I would say that you should speak candidly as possible about your strengths, desires, and how you are willing to learn and grow.
First, you should talk about your strength. Perhaps the most objective way to do this is by mentioning your achievements and awards. So, if you were on the dean's list, then say so. If you were the captain of a sport and showed leadership, then say so.
Second, you should talk about what you like to do. Hopefully your passion would be within that field. If so, that would be a great sign for the company.
Finally, show that you are willing to learn and work hard. All companies know that there is a lot to learn on the job. They do not want a know it all and they know that you do not know it all. So, show that you are willing to learn.