Stage Left, and Stage Right.
The areas to the sides of a stage (that the audience cannot see) are called the wings.
a stage with stairs on the sides
The passcode to play stage 28 on Bloxorz is 769721. The passcode to play stage 29 is 691859.
The whole area is simply called "backstage." The sides, to be specific, are called the "wings."
A Thrust Stage
On the sides
it is when the actors enter from the sides of the stage
They are called the wings.
A thrust stage.
The passcode to play stage 5 is 028431. The passcode to play stage 6 is 524383.
The passcode to play stage 19 is 119785. The passcode to play stage 20 is 543019.
The passcode to play stage 21 is 728724 The passcode to play stage 22 is 987319