(Not universally applicable, unfortunately.)
Literally: answer – disease – give – medicine
Alternately: Just what it says on the tin: giving someone medicine appropriate to the illness they are suffering from at the time. By extension, teaching people the lessons they need (especially moral lessons, or in a Buddhist context, Buddhist teachings) in a way appropriate to their personal character, aptitude, and situation in life.
Notes: This compound may also be given the Japanese-style reading 病に応じて薬を与える (yamai ni oujite kusuri wo ataeru). It has a number of synonyms, including 対症下薬 (taishou kayaku, “giving medicine against the symptoms”) and 因機説法 (inki seppou, “teaching (Buddhist) law based on the opportunity”).