This is a keycap with the number 1 written on it. You can see the keycap on the keyboard
⌨️ or telephone dial pad
☎️. It has a similar meaning to
☝️ and can be used to represent the number 1, or the winner of a competition
🏆🥇. Other keycap emojis:
#️⃣*️⃣0️⃣2️⃣3️⃣4️⃣5️⃣6️⃣7️⃣8️⃣9️⃣🔟