This icon is a part of a collection of Open in Window flat icons produced by Icons8. Icons follow the guidelines of iOS, Windows, and Android and are designed by a single designer, guaranteeing the consistent quality.
The object is a box with a line across the top so that it is two spaces with the one on top being very narrow. There are three dots on the left side of the top portion. There is an arrow starting at the bottom left corner of the large portion of the box and it points diagonally to the top right corner of the box.