Before you start a duel in Yugioh stardust accelerator what does the millennium item thing next to your name and deck name mean?

Answer 1

When you start a duel, there are basically 3 symbols: a figurehead, a deckholder, and a Millennium Puzzle. The figurehead represents the duelists and lists the name of said duelist next to it. The deckholder represents the deck the duelist is using and the name the duelist gave to the deck. And lastly, the Millenium Puzzle represents the duelist's rating (or in your case, your Wi-Fi rating) and lists how much rating they have next to it.