There is a sealed envelope with an arrow laying slightly above the envelope's bottom edge. The arrow has a curved end, and its front is pointing towards one side of the envelope.
This Reply 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 5,700 icons, all in the same style and quality.