It's a log of Nike reduced to a checkmark. The checkmark had a black outline and is white in the middle, pretty much looks like the logo on all of Nike's clothing.
This Nike icon is made in flat color style
. This format was developed by Icons8 designer team and became immensely popular for use in web and mobile applications. Feel free to download this icon in PNG format for free, or unlock other formats for $5. Unlike other icon packs that have merely hundreds of icons, this monster icon pack contains 6,200 icons, all in the same style and quality.