It's an icon with a paint bucket about halfway tipped over. There is liquid running out of the bucket because it is tipped partially over. There is a slash line running through the middle of the paint bucket starting at the top left through the bottom right.
This is a No Filling icon. We've made it in iOS style
, first introduced in iOS version 7 and supported in all later releases up until now (at least iOS 11). This style is based on thin two-pixel lines and is optimized for 50x50 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 13,300 icons, all in the same style and quality.