identifying linear transformations from their matrices

Question

Hoping someone can help, I'm currently working through some sample questions for my upcoming maths course. I'm stuck half way through question (b). I can see why its not a scaling or horizontal or vertical shear. But the second half of the question makes no sense to me. Can someone please elaborate on whats been done. Thanks in advance, the question and answer are below. Question and answer

Answer 1

The transform of the two standard basis vectors $(1,0)$ and $(0,1)$ is given by the two column vector of the matrices.

Using these, you can draw the transform of a square grid of side $1$, which is another grid with parallelogram-shaped cells.

From this graphical representation, you can easily identify the type of the transformation.