It can be a hyphen which you use to link prefixes example is co-founder
It can be a en dash which you use between number sequences example is 1,2,3,4 instead with a en dash is 1-4
Last one is a em dash which can mark none important words or show a break in the sentence example is I hope you day is amazing-except when you don’t smile- but you always smile
But the essay is supposed to be about you? how do we know your family background? education aspirations, and career goals? i’m afraid i won’t be able to help