Hi there, little one! North Downs are a type of geographical feature that you might see in some parts of the world. These are basically a group of hills or mountains that run in a north-south direction. They are called "downs" because they are usually covered with grass and are great places for grazing animals like sheep and cows.
Imagine you are in a big playground, and you see a bunch of small playgrounds that are set up in a straight line. Each of these little playgrounds is a north down. They go up and down like little hills, and they are all connected together. When you stand at the top of one of these north downs, you can see the other ones stretching out in front of you like a series of big bumps.
North downs are great for outdoor activities like hiking and biking. People can climb up and down them, and even run races along the tops of the hills. They can also be used for farming and agriculture since the grass provides lots of food for animals. So, in short, north downs are a bunch of grassy hills that you can explore and use for different activities.