This is a Switch Host icon. We've made it in iOS style, first introduced in iOS version 7 and supported in all later releases up until now (at least iOS 11). This style is based on thin two-pixel lines and is optimized for 50x50 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 12,800 icons, all in the same style and quality.
It's an icon of a computer screen that has been reduced to a small version of a computer monitor. It is a rectangle with hard corners sitting on a flat rectangle with a little rectangle in the center. Inside the bigger rectangle appears to be a three dimensional box.