Ok kiddo, so a "genizah" is a special room in a synagogue where Jewish people put old and worn out religious books or papers.
But why do they do that? Well, in Jewish tradition, the written word is really important and is considered to be holy. These writings can include things like prayer books, Torah scrolls, or even personal letters.
When these documents get old or damaged, they can't just be thrown away like regular trash because that would be disrespectful to the writing. So instead, they are placed in the genizah, which is like a special storage area where they are kept until they can be properly disposed of in a respectful way.
Sometimes, people also put things in the genizah if they have certain words or names of God written on them, because those things are considered too holy to just throw away.
So basically, the genizah is a special place where Jewish people can store their old and worn out religious writings before they are respectfully disposed of.