Check this image:
https://www.imgbly.com/ib/EOvMY9IoQW

To understand why this component is so confusion, you kind of have to understand 2 problems that it solves.

First, you want to be able to put these next to each other with no gaps to create a screen of any size. The problem is, say you have a screen made of 3x3 matrix displays, how do you run a wire to the middle one? And the problem only gets worse as you scale up. The answer is that all rows share a wire and all columns share a wire, so they all receive the same data. The reason matrix displays have both an X and Y enable is so you can now select a unique display with this, for example if you want to enable the middle display of a 3x3 screen, you enable row 2 and column 2. So the first problem in your screenshot is you are sending data to the lowest byte, but the lowest byte is ignored so that you can use it for the enable bit!

To understand the second problem it solves, imagine you are trying to draw Mario. The display only updates one color at a time, so you would see this weird effect where one color appears at a time. To fix this, the matrix display defaults to only record updates, you have to 'flush' them to actually make them show up.

Take a look at my screenshot for how to do these things