This functionality is used to take the user back to the previous state of the project. User can find this by clicking on toolbar Edit | Undo or press Ctrl + Z on the keyboard. In case the user needs to retract the undo option, they can do that by using redo option.
To redo the changes, click on the toolbar Edit | Redo or press Ctrl + Shift + Z on the keyboard.
Track the changes done in the project by opening the History window. The History window is updated as the Undo / Redo is used.