The "Today's Words" page lets you see all of the words that you want to study today. This set of characters should contain your most recent unfamiliar words. This feature is extremely important and it should usually be the first thing that you use study Chinese in the FullChinese app:
If you press on the "See All" button, you can study Today's Words by quizzing yourself. As shown below, you can test yourself via a Read, Pinyin, or Write Quiz.
The video below contains more information on Today's Words: