That's quite a mouthful -- What exactly is a renewable natural resource and why are they so great?
As for renewable natural resources, they're pretty easy to understand. Let's break the phrase up.
When something is renewable, it means that it can be replaced, or brought back. Trees are renewable because they grow back after they've been cut down. So if you manage your forests in the right way, you can grow back the trees you cut down forever!
When something is natural, it means that it comes from nature. Trees come from nature!
When something is a resource, it means that it's valuable to humans for making other things. Trees and wood are resources because there's lots of valuable things we can make from wood.
So, when you put the whole phrase together, a renewable natural resource is something that comes from nature that's valuable to people, and can be continually restored.