1. that is so; that is right; it looks to me; that's my impression
そうです、そういえば、まだ話の途中でした。That's right, come to think of it, we were still in the middle of the conversation.
2. people say that; it is said that; I hear that
after plain form of a verb or adjective
問題発生だそうです。It is said that a problem has occurred.