Displacement is a vector quantity whereas distance is a scalar quantity.
So imagine you run a standard 26-ish mile marathon, along any path you care for, but where the start and finishing line are the same.
If you complete the race, you have travelled a distance of 26 miles but have undergone a displacement of zero. Because you are back to where you started.
In that sense, getting back to your question, the number line is a bit like a vector quantity.
Imagine you are standing on a number line that runs East- West, and you have as the Origin where you are right now.
If you run 1 metre due West and then stop, your displacement is
In either case you have covered a distance of