Currently, there are about 2900 commonly used English words. You should learn new words before playing games because those games are related to the words you just learnt.
You can change the number of words, number of levels and translation language for each lesson. It is useful to control your progress.
There are many game types: find word by meaning or translation, find meaning by word, spell word by voice, true or false questions, matching, etc. They are randomly picked up for each level.
After finishing each lesson, the score will be shown. You can view the complete score for all lessons in the main app.
You can review the last lesson to study words and play games again in order to improve your understanding.
If you are an educator, you can ask your students to export scores as CSV files for reporting purposes.