This page shows the different variations of the Wstążka zakładka from an Icons8 icon pack. Feel free to resize and recolor the icon, and then download the icon in PNG format for free. Icons are available in PNG and vector.
The image appears to be a flag or banner. The basic shape is a rectangle with the long sides standing vertically. At the bottom instead of a straight line to close the rectangle the center point of that line dips up like a triangle is missing from the bottom of the rectangle.