Create a Ui/Ux Desing for an APP

This is an App just to listen and read phrases in English and their translations. Screen 1 - Splash screen with logo Screen 2 - Login screen with the option “sign in with google” and “Sign in later”. There will also be the app logo and the English icon. Screen 3 - List of countries and their flags icons. It must be clear that the users will learn English and they need to select their native language to continue. Screen 4 - This screen is the most important, there users will interact with the app. These are the elements: A play/loudspeaker icon where the user will listen to the phrase. A text box (max 80 caracteres) with the text in english. The text appears firstly hidden, then the user taps to show the text. We need an icon with the EUA/British flag to indicate that there is the text in english. A text box (max 80 caracteres) with the text in the user native language selected in the previous screen. The text appears firstly hidden, then the user taps to show the text. We need an icon with the native country flag to indicate that there is the translated text A button to remove the ads. When users press it, it shows an option to buy the feature. A button (like a padlock) to unlock the current phrase. When the user taps on this option it will show a pop-up with two options: Watch a video to unlock the next 30 phrases.[video reward] Unlock the next 1000 phrases [in-app purchase] A horizontal scroll line to select the current level [1000 levels] There will be two kinds of phrase icons: selected (current) and unselected. Another horizontal scroll line to select the phrase of the selected level [1000 phrases] There will be two kinds of phrase icons: unlock and locked Lateral arrows < > in the middle of the screen to go to the next phrase Icon of a hidden lateral menu with the following options: Select language (Back to previous screen) Remove ads Share Rate Privacy Policy A space for a Google AdMob banner at the end of the screen. Screen 5: just plain text to insert the privacy policy. Notes: The app must have a clean design with light colors. My main concern is about the navigation to select the levels and the phrases, considering that there will be 1 million o phrases divided in 1000 levels. You are free to do anything you think that will improve the navigation. Users are able to select the items of screen 4 in any order. You must use as few text strings as possible, because it is a multi language app. You should use intuitive icons instead of text as much as you can. I need all flag/country icons of the screen 2 and 3 of the following countries: Brazil Bulgaria China Croatia Czech Republic Denmark Estonia Finland France Germany Greece Hungary India (Bengali) India (Hindi) India (Tamil) India (Telugo) Indonesia Israel Italy Japan Korea Latvia Lithuania Malaysia Netherlands Norway Poland Romania Russia Saudi Arabia Slovakia Slovenia Spain Sweden Thailand Turkey Ukraine USA/GB Vietnam