This is a teacher standing in front of their blackboard. The board has a shelf on it to hold chalk or dry erase markers. The teacher has his/her mouth open wide and is teaching students how to sing. He/she has musical notes coming out of his/her open mouth.
This Singing 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.