So imagine you're playing with your toy car and you accidentally drop it down a sewer grate. You can't reach it and you start to feel sad because your car is gone. But now imagine someone passing by sees you crying and, even though they don't know you, they decide to help you get your car back. That person is showing a "duty to rescue."
A duty to rescue means that if someone is in danger or needs help, other people have a responsibility to help them if they can. We want to make sure that everyone is safe and taken care of.
So, for example, if someone is drowning in a swimming pool and you know how to swim, you should try to help them instead of just watching them struggle. Or if you see someone hurt on the street and you know how to apply a bandage or call for help, you should do that too.
Of course, we can't always help in every situation, but if we can, it's important to try. And in some places, there are actually laws that say you have a duty to rescue - which means you can get in trouble if you don't help when you could have.