Hieroglyphic Luwian is a very old way of writing things that was used by people who lived a long time ago. It is called "hieroglyphic" because it uses pictures to represent words and ideas, kind of like how we use emojis today. It is called "Luwian" because it was the language that the people who used it spoke, kind of like how we speak English or Spanish today.
These pictures would be carved into rocks, walls, and other hard things, so that people could read them and understand what they were saying. They would use special tools, like chisels, to make the pictures very clear and easy to see.
The pictures would represent things like animals, people, and objects that were important to the people who used them. For example, a picture of a bird might mean "flight" or "freedom", while a picture of a person might mean "leader" or "ruler".
Because this way of writing is so old, it can be difficult for us to understand what it means today. But archaeologists (people who study history and old things) work very hard to try and figure out what these pictures meant, so that we can learn more about the people who used them and their culture.