This is the Widok miesiąca 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.
This is a series of rectangles in which you can draw in whatever you want into the days. It's a bunch of lines going criss-cross, as in one goes perpendicular and the other vertical. They do this until they make a pattern in which can be written in between.