This is a red cross. It means rejection, cancellation, π² prohibition and π error. Similar emojis: β cross button, βοΈ multiplication sign. Related emojis: β tick button, βοΈ tick, β οΈ warning, prohibition.
The Internet is a free creative platform, but we also have to learn to protect our own works, so we often see,"This work is reproduced β secondary transmission βReject plagiarism!β
Many Christians have a cross marked β in ashes on their foreheads.