Before a long, long time ago, people didn't have the same languages as we do now. These languages were called "pre-Indo-European", which means they existed before the time when people who spoke the language family called "Indo-European" came around. These pre-Indo-European languages were spoken by groups of people who lived in Europe and other regions around the world. They probably didn't write their languages down, they only spoke them to communicate with one another.
These pre-Indo-European languages were very different from the languages we speak today. For example, some of them had sounds that we don't use anymore, and they didn't have the same words we use now. A lot of these old languages are now extinct, which means nobody speaks them anymore. But some still exist, like Basque, which is spoken in parts of Spain and France.
People who study these pre-Indo-European languages are called linguists. They try to learn as much as they can about these old languages by studying things like fossils and cave paintings, because these are clues left behind by the people who spoke them a long time ago. By studying these clues, we can learn more about the history of the world and the people who lived in it a very long time ago.