This About 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.
It is a speech bubble with the letter "i" in the center. The bubble is not an exact circle, but rather a horizontal oval. The letter "i" is lower case, and one would think that by seeing this icon you would be informed about a certain topic presented with it.