It is a circle with a horizontal line directly in the middle of the circle. The horizontal line stops slightly before reaching the edge of the circle so no part of the line actually touches the circle itself.
This is the Minus 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.