Okay, let's pretend you have some friends who are called Arvanites. They are a group of people who live in some countries in Europe, like Greece and Albania. But Arvanites have a very interesting history!
A long time ago, there was an empire called the Byzantine Empire. This empire was very big and powerful, and it lasted for a really long time. The people who lived in this empire spoke a special language called Byzantine Greek. This language was a mix of Greek and some other languages, and it was very different from the Greek we hear today.
Now, the Arvanites are descendants of the people who lived in the Byzantine Empire a long time ago. When the Ottoman Empire (another big empire) took over Greece and Albania, many people had to leave their homes and move to different places. Some of these people were Arvanites and they decided to move to other countries where they could live in peace.
Nowadays, Arvanites still exist and they speak a special dialect of Greek that is a little bit different from the Greek that we hear in Greece today. They also have some special traditions and cultural customs that they keep alive, like their dances and songs.
So, to sum up, Arvanites are a group of people who are descendants of the people who lived in the Byzantine Empire a long time ago. They have their own language and culture, and they live in different countries in Europe.