Passing in sociology means pretending to be something or someone you are not, usually related to race or gender. Just like how you might play "dress up" and pretend to be a princess or superhero, some people might dress, act, or speak in a certain way to make others think that they are a different race or gender than they actually are.
Sometimes people do this because they feel like they will be treated differently or unfairly if others know their true identity. For example, someone might pass as a different race if they think they'll get a better job or be treated with more respect. It can also happen because someone doesn't feel like they fit in with their own race or gender, so they try to fit in with a different one instead.
Passing can be a complicated issue because it can involve lying and deception, but it can also be a way for people to protect themselves and find a sense of belonging. It's important to remember that everyone deserves to be accepted and respected for who they truly are.