Translation turns one Sequence into vendor source text. The available targets come from the installed provider extensions: CODESYS ST, Siemens SCL, Rockwell ST or Ladder, and Fanuc TP. If more than one is installed, you are prompted to pick.
Using the button: while editing a .seq file, click the Translate to Target Language button (swap arrow icon) in the editor title bar.
Using the Command Palette: run AutomationView: Translate to Target Language.
The command only appears once at least one translation provider is installed. To produce a deployable project file instead of source text, use Generate PLC code.