Cool Words gives you 2 learning modes:

Mode 1 - learning by listening

In this mode, listen to the correct pronunciation of the words. You can listen 100 words in less than 5 minutes.
In the settings you can adjust your daily goal or the way the words are played

Mode 2 - learning by testing

Test mode doesn't stress you in any way! A word will appear and you will decide for yourself whether you can translate it or not. Then you will see the translation of the word - and you will judge for yourself whether you knew the word or not.
By default, you have 5 sets of tests scheduled per day (you can adjust your goals in the settings).
If you have an Apple Watch - you can also test yourself there.

Learning reminder

You can get a reminder to study up to 5 different times during the day!
It will not happen that someday you forget to fulfill your plan.

Widget

Put a simple overview of how you fulfill your daily plan on your phone's desktop. Clicking on this so-called widget will also launch the application.