Persuade your reader by explaining how your qualifications, activities, experiences, or any other factor make you a great fit for this university. Every thought and word has to count, as the whole essay is short, and the conclusion is the shortest part of all. Only mention an aspect of the school if it directly relates to something about you. Obviously, the reader knows more about the school than you ever will, and doesn't need you to go on and on about it.
Use positive words and tone wherever possible. You want the readers to remember you and your essay in a favorable way. When they finish your essay, you want them to link your name, application, and essay together with a clear picture in their head that shows you in the best possible light.
Avoid using cliched phrases like "finally" or "in conclusion," as they indicate a lack of experience in writing and don't convey any individual meaning. Also, do not restate or summarize anything as it wastes valuable space. The last thing you want is to bore the person considering you for the university.
Bring your passion through on paper in a genuine way that comes across to the reader. Maybe the passion is for the career you expect to have after you get your degree, or the impact on the world that an education at this school will enable you to make. If you have trouble putting that passion into words that make sense on paper, then talk to a family member or close friend about it. Often, a conversation with another person can help bring surprising words out of you. Sometimes the person you are speaking to can help you work out why you want to go to that school.