Answer:
The shape really appears in my mind as exactly as the side shows. From the top, it would appear to be a square, first of all because no shadows, and because the slant is facing up. From the front, it would be the exact same thing as I just described. Only from the side can you see that it's a square, wedge triangle.
I have provided an example of this explanation in visual terms, based on the image you provided. I tried to draw it in 3D, but I'm just not a really great artist, so I hope you can make out what I was trying to depict ;)
Hope I helped!
If you have any further questions, please comment on this answer and I'll try to respond as soon as I can!