It's a logo of Queue reduced to the top half of three people standing behind each other. It looks like three people waiting in line. Which is similar to what a queue is.
This Queue icon is made in Material Design style
developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 6,000 icons, all in the same style and quality.