This is the XLS 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's a rectangular looking shape with the top right corner folded in slightly, so it technically looks like a trapezoid, with a right angle drawn into the top-right corner (if you are picturing a trapezoid). There are three letters on the inside positioned in the center, more so to the bottom than the top, they are X, L, S, in that order.