It's the capital letters 'MPG" drawn inside of a rectangle. The rectangle is drawn to look like a sheet of paper with the upper right corner creased and folded down to the front. The letters are centered from left to right and closer to the bottom than the top.
This is a MPG 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.