The icon shows that weapons are not allowed. It is a handgun with a diagonal line going through it. The line goes from the top-left of the gun to the bottom-right.
This is a No Weapons 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.