Pronoun agreement can be trickier than it might seem on the surface. The rule is that we must make sure our pronouns agree in number and gender with the nouns they are replacing. For example, when we write a sentence about a girl named Sophia, we would use she as the pronoun to refer to her.
But things get a little more confusing when we are talking about a kind of abstract person, and the “rule” on this subject has recently changed in most circles. In the recent past, to avoid sexist language, we didn’t want to write only he or only she, so we resorted to the somewhat awkward he or she. For example:
But, with the now universally accepted singular they, we can simply use the pronoun “they” to refer to someone of any gender.
Many people also prefer to use the singular pronouns they/them rather than gendered pronouns. This is a great example of how languages like English change and adapt as times change. It’s really pretty exciting!