Territorial claims in Antarctica are like pretend battles among grown-ups for a big piece of ice which nobody can see. Imagine a big playground where everyone wants to have their own little place to play with their toys, but in this case, the playground is a big frozen continent.
Many years ago, some countries decided that they wanted to have a piece of this playground for themselves. They drew invisible lines around certain parts of Antarctica, like somebody drawing a circle around their favorite toys. So, if anyone wanted to play around in that circle, they would have to ask the owner for permission.
Now, here comes the tricky part - nobody really owns Antarctica. All of these countries claim to own a piece of it, but nobody can own it because the continent is too big and too harsh to have people living there all year round.
So, every year, when the grown-ups gather to talk about these pretend battles, they just agree to disagree and keep their imaginary circle around their claimed territory. Nobody can really do anything about it, so they just live peacefully around each other, like different kids sharing the same playground, but having their own little space to play.
That's basically it - territorial claims in Antarctica are just like imaginary circles drawn around different parts of the continent, where nobody can really enforce the ownership of these territories. So, in the end, everyone just keeps playing nice and sharing the big playground.