A strong college application tells a student’s story - who they are and where they are going. The purpose of the essay is to give admissions committees a sense of your personality and what you'll bring to their school's community. In short, the essay contextualizes your application and shows what kind of person you are outside of your grades and test scores. The personal statement is your chance to stand out as an individual.
The other roles of the short answer essays on an application include:
Evidence of writing skills
Explanation of extenuating circumstances
Reasons for applying to the school
Essay prompts are generally pretty open ended and can be approached in a lot of different ways. Below is more detailed information and resources for crafting an impactful personal essay.