Meaning
A solid purple square, part of the emoji version 12.0 colour set. It means purple and adds a rich, playful tone to colour grids.
It shows up in pixel art, aesthetic dividers, colour-coded study plans and fandom colour schemes: “Study plan: 🟪 history, 🟦 maths, 🟩 English” In game-style rankings it often marks a rare item. The round version is 🟣, and 💜 adds affection.