The Learning Status statistics are designed 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
For more information on levels, please refer to the article linked here.
Informational lines are excluded from the Learning Status statistics as they only reflect the maturity of spaced repetitions - and informationals are not studied with spaced repetition.
A high number of variations in the learning stage may mean that you risk overloading yourself with reviews. Be careful to pace yourself and keep on top of reviews before learning new material.
If most variations are in the mature stage, it means you have really begun to master the course content. Reviews will come round less frequently, but staying on top of them will keep everything in your long-term memory.
A high number of variations with the difficult status means that you are struggling with the course content. Reviewing the course text, analyzing positions with a computer, or pausing material that is too difficult are all viable strategies. The key thing to do is to avoid endlessly repeating material that you are not able to master as this will end up occupying all of your study time.