As with all projects, bugs and requests for enhancements and new features accumulate. Many of them only involve a couple of weeks worth of effort, but the primary developers are busy enough that there's just not enough time to get to them. Dealing with a few small bugs, a couple of medium enhancements, or a single large new feature (and including tests and documentation) is a tremendous way for inexperienced programmers to get their feet wet, gain experience, and sharpen your Python skills.
The idea here is to choose a reasonable set of bugs to tackle: not too hard and not too easy. You can get advice from the mailing list as to the difficulty of various bugs, but judging how long it will take to do a task is one of the skills that young programmers must develop.