In Chinese “学”usually means study,at school or by yourself, it is a concept with more extensive meanings.such as "学中文”maybe learn it at school maybe study by yourself."学”often used in our oarl language."学习”always means study more formal, usually means learn something at school.or some activities releated with school."念书" have two meaning ,one is study at school, the other is reading books loudly.but we never say "我念书中文”.so if you are no sure of which word is better use "学”maybe help you making less mistake.