The balance of power is like playing on a seesaw with your friends. You want to make sure that nobody is too heavy or gets too much power, otherwise, they might make all the decisions and you won't get to choose anything. So, you and your friends try to balance your weight on each side of the seesaw, so that it stays level and nobody has too much control.
In international relations, countries also try to balance their power. They want to make sure that one country doesn't have too much power, otherwise, it could be a danger to other countries. So, they try to balance their military, economic, and political power with other countries, so that no one gets too powerful and makes all the decisions for everyone else.
This balance of power helps to prevent wars and conflicts because no one country can dominate others. It also encourages cooperation and negotiation because countries need to work together to maintain the balance of power. It's like making sure that everyone has a fair and equal say in what happens in the world, just like you and your friends on the seesaw!