This is a Friday 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 12,300 icons, all in the same style and quality.
It's a logo of a calendar page. There are two rings on top then a page coming down with a line near the top of the page. On the larger lower part of the calendar page are the letters "Fr" representing Friday.