I only have a rough idea about this field; I can't call myself an expert.
Tips
usage
略知一二 is typically used modestly to downplay one's own knowledge. It's a humble expression - even experts may use it as a form of polite understatement.
memory
略 (roughly/approximately) + 知 (to know) + 一二 (one or two things). Literally: 'roughly knowing one or two things'.