This app is structured like a book, with a new sentence on every page (see images). You have explanations (at the top of the page) and a list of new words (at the bottom).
Read the explanations and the sentence to be translated and press on the 'Press here to show the translation'.
IMPORTANT: Each time a translation is revealed, a new button will be enabled and explained. It is not an error. This is done so as not to overwhelm the new user.
Move back and forth between pages using the arrows at the bottom.
Do not rush through the sentences, read everything carefully and make sure you understand everything before you move on.
Read more in the 'How to use the app' section in the menu.