Your progress for each level (Beginner, Intermediate, Advanced and Expert). It also shows the number of subtopics you've learned fully so far.
A subtopic can be considered as a learned subtopic if ALL the games of that subtopic are 100% complete.
A 100% complete game is a game that has a whole progress circle on the main screen. For a whole progress circle, you need to give only correct answers during the game.
Note: These statistics are only for the current device.