The Learning Status is to help you understand your progress through a course. The meaning of each status is as follows:
Not learned - The number of variations left to study
Paused - The number of variations that have been paused
Learning - Variations that you are still learning (levels 1 to 7)
Mature - Variations that you know well (levels 8 and above)
Difficult - Variations that you frequently get incorrect
The levels are explained in our article on spaced repetition linked below. If you use custom or cyclical scheduling, the time it takes to get to 'Mature' learning status will vary.