If you’re trying to understand why people use pronouns like they/them when they look like a she/her or he/him, let this guide enlighten you
TLDR: it’s about what they identify as so when you respect their choices as to what to refer to him, her, or they, you respect the individual
Reference https://pronouns.org/what-and-why
What Are Pronouns? Why Do They Matter? — Pronouns.org Resources on Personal Pronouns
"Hi! My name is ____ and my pronouns are ____." Pronouns.org offers ample practical resources and information to help you understand personal pronouns, how to share/ask/use pronouns, correct mistakes, and more!