A lattice path is like a path on a grid. You can think of it like a picture or a maze that is made up of lots of squares in a pattern. You have to start at the beginning with one square, and trace your way along the path until you get to the end. To get from one square to the next, you can either go down or to the right. If you try to go up or to the left, you will not be able to get to the end.