Well, that depends on what kind of a student you are.
You probably fall into one of the following three categories.
Your essay is what will set you apart from the other 99. Or maybe you're a lacklustre student with poor grades and no extracurricular activities. The college or university usually admits a few students with weaker qualifications to give a break to students who stand out in some non-academic way, who look like they might really do something special if given the chance.
XYZ might bring something interesting and valuable to the school.
And that if they give you the opportunity to get an education at their college or university, you'll go out into the world after graduation and do meaningful things with it.
Always remember that your conclusion should be concise and there shouldn’t be anything new included in the conclusion or something which would contradict what you’ve already took a stand about.
She might be a deep thinker who has made some mistakes or has had some bad luck, like family problems.
Or maybe nearly all of the students at the university are the same --homogeneous-- in some way, culturally, racially, economically-- and XYZ would bring a perspective to class discussions and study groups that others won't have. The concepts which you've already learned in your junior English classes about essay writing apply to your college application essay as well – brainstorm, organize effectively, write with personality and emotional commitment, use vivid word choices, and proofread your work for conventions errors. And here's the best single piece of advice I can give you: Start early, so that you can revise thoroughly and meaningfully.
The university wants that, not out of generosity, but to create a lively intellectual environment where not everyone sees through the same cultural lens. If you're a chronic procrastinator, make yourself start early so you can write more than a single draft. You've probably written several essays for school.
If you think you "write best under pressure," don't kid yourself. And your teacher, I would hope, will have talked to you about how to organize an essay.