Defencism is like when you are playing a game with your friends, you want to make sure that you are protected and safe from any harm or danger. Similarly, defencism is the idea that a country or a group of people should protect themselves from any harm that might come their way.
Imagine you have a fort or a castle that you live in, and you want to defend it from any enemies who might try to come and take over. You would build high walls, put guards at the entrances, and have weapons and tools to help you fight off any attackers.
In the same way, defencism means that a country should always be ready to defend itself from any harm that might come its way. This could mean having a strong military, having good relationships with other countries, and being prepared for any natural disasters or emergencies that might happen.
Just like you want to be safe and protected when you play games with your friends, defencism is the idea that a country should always be prepared and have a plan in place to keep its people safe and protected from any harm or danger.