LGBT erasure is when people try to make it seem like LGBT people don't exist or are not important. It's like when you draw a picture and then someone else comes and erases it so that you can't see it anymore.
For example, sometimes people might say things like "there are only two genders" or "marriage should only be between a man and a woman." These statements erase the existence and importance of LGBT people who don't fit into those narrow definitions.
Not acknowledging LGBT people or denying their rights is also a form of erasure. When people erase LGBT people, it can make them feel invisible, unwanted, and like they don't belong.
LGBT erasure is not fair or kind, and everyone deserves to feel seen and accepted for who they are.