Shu'ubiyya is a big word that means when some people think that their language or their culture is better than other people's language or culture.
Imagine you have a red toy car and your friend has a blue toy car. You might think that your red car is better and cooler than your friend's blue car. That's kind of like how some people in the past thought their language or culture was better than other people's language or culture.
But here's the thing - just like how both red and blue toy cars can be awesome in their own ways, all languages and cultures are special and important. We should celebrate and learn from each other's differences instead of thinking that one is better than another.