"말을 잘 안 하다" can have different meanings depending on the context. It could be used to describe someone who's not talkative. e.g. 그 학생은 말을 잘 안 해요. The student doesn't talk much. The student is quiet. The student is not talkative. Or this could be also used when there isn't much conversation going on between two or more people. e.g. 우리는 서로 사실 말을 잘 안 해요. We don't actually talk to each other that much.

지금 means now and 같이, in this specific context, means 'like' so 지금과 같이 means like now or like these days. 젓갈 is Korean traditional fish sauce and 후반 means 'in the late ~' so as you can tell, 18세기 후반 means 'in the late 18th century'. And 보편화 means generalization so 보편화되고부터 means 'after Kimchi being generalized'. 정화 means 'purification' or 'purify' therefore 과정을 거쳐* 정화되고 would mean 'after it gets purified in its process' Hope it would be helpful:)