This Toggle On 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 4,400 icons, all in the same style and quality.
This icon looks like a switch which can be toggled by sliding left to right. The border of the switch is a rounded oval, and the button itself is a circle which slides between two positions from left to right. The icon shows the circle in the right position.