These are rollerblades. It is a shoe with very small wheels attached to it at the bottom of the shoe.
This Rollerblade 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 6,100 icons, all in the same style and quality.