Polygons in a coordinate plane will make it easy to find the distance between the points of the polygon. It also helps in finding the perimeter and area of the polygon.
We need to know that a horizontal line goes straight from left to right, a vertical line goes from up to down and the distance is how far apart the two points are.
If we have a straight horizontal line then the $y$ coordinates will remain the same. Similarly, for a straight vertical line the $x$ coordinates will remain the same.