The graphics is nice but the explanation is just terrible. There is a huge gap between the first part explaining vectors and then the part explaining eigenvect

The graphics is nice but the explanation is just terrible. There is a huge gap between the first part explaining vectors and then the part explaining eigenvectors. "If you can draw a line through (0,0), v and Av, then Av is just v multiplied by a number λ; that is, Av=λv." That makes no sense. How do you draw a line through a point to "v and Av"? What does "v and Av" even mean in that context?