This is a keycap with the number 0 written on it, which corresponds to the Chinese character zero. You can see the keycap on the keyboard
⌨️ or telephone dial pad
☎️. 0 usually symbolizes beginning, new things, or empty
🈚️. At the annual New Year's countdown
🕛 event, the moment the number
🔢 changes to 0 is both the end of the year
🔚 and the beginning of a new year.