Okay kiddo, so a stock route is like a highway, but instead of cars driving on it, it's used for animals like cows and sheep to walk on. People use stock routes to move large groups of these animals from one place to another, usually in search of better grazing land or water sources.
Think of it this way: when you take a family road trip, you probably stop at different rest areas or restaurants along the way to make sure you have enough food and water, right? It's the same thing with stock routes. People who move animals along these routes need to make sure there are enough resources like grass and water for the animals to eat and drink along the way.
Stock routes can be very long and go through many different areas. People have been using stock routes for a very long time, sometimes for hundreds of years!