"Подожди, ты второй!"

Translation: Wait, you are second!

[Tina_in_Bristol]

Is this effectively saying: "Wait your turn!"? I don't quite get it.

[zirkul]

Most likely.

[SteveBKK]

You are next?

[R_Andersson]

I think that would be «Ты следующий/следующая» or «Вы следующие».