Well, imagine you're in kindergarten and you really like your toy truck. You like it so much that you won't let anyone else play with it, and you tell all your friends that it's the best toy truck in the world. That's kind of like Austrian nationalism.
Austrian nationalism is when people from Austria feel very proud of their country and culture. They might think that their country is the best in the world, and they want to protect it from other countries. This feeling of pride and protection is what makes them "nationalists".
For example, if someone is an Austrian nationalist, they might want their country to have its own laws and rules, rather than following rules from other countries. They might also want to preserve traditional Austrian customs and values, like the music of Mozart or the cuisine of Vienna.
Sometimes, nationalism can become extreme and turn into things like racism or xenophobia (fear of people from other countries). That's why it's important for people to be proud of their country without hating or discriminating against others.
So, to sum it up: Austrian nationalism is when people from Austria are really proud of their country and want to protect its traditions and values. But it's important to remember to be kind to people from other countries and cultures too.