This is the Calendar 11 icon for Windows 10. Here we go. Optimized for 32x32 px, these are the simplest icons in the line style. Downloadable formats are PNG and SVG, among others. Icons8 icon pack is unique in providing a huge number of icons designed by the same team of four designers who create the new icons every working day in the same style and with the same quality. Same cool as the Bat Face, huh.
It is the number 11 contained within a rectangle. It appears to be a page from a calendar that is bound at the top. There are two binding rings represented by two small rectangles on the top. The date, which is 11, is written on the page below the binding.