It's an icon that is a message balloon. It is a message balloon like they use in cartoons in newspapers or magazines. It has an arrow pointing to the right inside of the balloon.
This is a Topic Moved 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 13,900 icons, all in the same style and quality.