The image is of a four sided square. The square is completely closed with no breaks in the lines. There inside of the square is blank. There is nothing on the inside or outside of the square.
This Full Image icon is made in Material Design style
developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 6,000 icons, all in the same style and quality.