Walking distance measure is a way to figure out how far away things are when you walk to them. Imagine going on a walk with your mom or dad and they ask you, "How far do you think we've walked?" Walking distance is the answer to that question!
So when you want to measure how far away something is, you start by drawing a big circle around where you are standing. This circle is like a big hug that you give to everything around you, saying "This is all the stuff I can walk to!"
Then, you count how many steps it takes you to walk from your circle-hug to the place you want to go. Each step is like a little hop forward, so you need to make sure you're counting the right number of steps. Sometimes you can use an app on your mom or dad's phone, instead of counting steps, to figure out how far you've walked.
Once you know how many steps (or the distance reported by your app) it is from your circle to your destination, you can say that's how far away it is. Now, you might be wondering, "But what if there's a big wall or a river in the way that I can't walk across?" Well, sometimes you have to take detours around those things and that's called a longer walking distance.
Overall, walking distance measure is a way to figure out how long it takes to walk somewhere, by counting the number of steps or measuring the distance between you and where you need to go, and it helps you to plan how to get somewhere by foot.