This is just a photo of the letter X. It is one diagonal line going from the upper right to lower left, going through another diagonal line going from left to right.
This Multiply icon is made in Material Design style
developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 6,000 icons, all in the same style and quality.