When explaining a Newton, the kids must be told it is an SI Unit of measurement, from the International System of Units, which are an internationally recognized standard. After that, the concept of force has to be explained. This can be done with a couple of examples or better yet, with Newton's Second Law of Motion.
Newton is the unit of force in the International Systems of Units. Force is the product of the mass of any particular body and its acceleration. Hence when we talk about one Newton of force, we're focusing on a body that has one kilogram of mass and is travelling with an acceleration of one meter per second squared.
Explaining tough science concepts to kids can often be a very difficult thing to do. The key to do this is to divide the answers into a couple of phases, and then go about each sequentially. This is going to help the kids absorb each bit easily, resulting in a complete understanding.
Once the concepts of Newton as a unit and Force as a product of mass and acceleration sink in, merge them together to explain that a Newton actually is a unit of Force, which helps science students throughout the world in understanding the physics better.