I dont think this actually 'translates' text.
IIUC, it will change a block of text to be as if it were printed with a keyboard from a different language.
i.e. if, on my german keyboard, I start typing as if it were an english keyboard (& forget to change the keyboard settings) I can select the typed text and the app will convert it to 'as if it were typed on an english keyboard'.
But I think you understood that bit anyways