This Microsoft SharePoint 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 4,300 icons, all in the same style and quality.
It is a bold letter S in side a square slanted so that far left side appears to be further back than the near right side. There are two circles evenly spaced attached to the near right side and from then a simi circle is drawn to a 3rd circle of the same size as a point.