The gesture of crossing two fingers can pray for good luck and success. It is often used to express a prayer for God's protection. The cross of two fingers is actually the shape of a cross, which means praying for God's protection and good luck. Some athletes (such as players) often use it. It's also often called "good luck and success".
Today, even those who don't believe in this superstition often use it to express the hope that things will work out as they wish. On various social media, there is even a dedicated Emoji.