Classical Tibetan is a way that people in the past used to write and speak in Tibet. It's kind of like how grown-ups might talk or write in a fancy way that kids don't usually use.
Just like how there are different types of writing and talking in English, there are also different types in Tibetan. Classical Tibetan is one of them. It is very important because it was used to write down a lot of important stuff like prayers, religious texts, and old stories that people still read and study today.
If you were to listen to someone speak in Classical Tibetan, you might notice that they use different words and sentence structures than people do when they speak modern Tibetan or other languages. It might sound a bit strange or different to what you are used to hearing.
Overall, Classical Tibetan is an important part of Tibetan culture that people still learn and study today. It helps people understand the history and traditions of Tibet through its old language and stories.