This icon is a part of a collection of W górę w lewo 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. Both PNG and vector are available.
This is an arrow pointing up and left (or -45 degrees if up is 0 degrees). It's a basic line going from the bottom-right to the upper-left and then an arrowhead on that line continue to point to the upper-left.