Okay kiddo, imagine a big machine that makes cookies. Normally, when the machine is working properly, it makes lots and lots of yummy cookies! But sometimes, a part of the machine breaks or stops working right. This can cause problems and the machine might not be able to make any cookies at all.
Criticality is like checking the machine to make sure it's running correctly. If we say the machine is in a critical state, it means that something is broken or not working right and we need to fix it as soon as possible so we can keep making those yummy cookies.
This can apply to lots of different things, like your toys, your house, and even the people around you. When something is in a critical state, it means we need to pay very close attention to it and take action to fix it before it gets worse.