Have you ever seen pictures or drawings of different things? Maybe a picture of a cat, or a drawing of a house? Gardiner's Sign List is kind of like a big book of pictures, but these pictures aren't just things you can touch or see in real life. They are pictures of symbols that people used to write down words a long time ago.
Back in ancient times, people didn't have computers or phones to text or email each other. They used something called "hieroglyphs" to write things down. Hieroglyphs were symbols or little pictures that stood for words or ideas. So if someone wanted to write down the word "cat," they would draw a picture of a cat instead of writing the letters C-A-T.
Gardiner's Sign List is a big, organized list of different hieroglyphs. They're organized in a special way so that people can find the right picture symbol to use for the word or idea they want to write down. For example, if someone wanted to write down the idea of "motion," they would use a symbol of a person or animal walking or running, because that shows movement.
So Gardiner's Sign List helps people today learn about hieroglyphs and how people in ancient times used to write. By looking at the symbols in the list, we can learn a lot about their language and culture from a long time ago.