Meaning
The capital letters END sit above a small arrow pointing left, matching the other word-and-arrow signs ON!, SOON and TOP. Literally it means the end: of a list, a story, a thread or a period of time.
People drop it at the bottom of a long post or a numbered thread to show nothing more is coming, or to close a chapter with a little drama: “Last exam handed in, semester officially over 🔚” It pairs well with 🏁 for finishing or 👋 for signing off.