そうです is often used in conversations. You can say はい、そうです (Yes, that’s correct) to give an affirmative answer regardless of the words used in the question.
Apparently I say そうですね a lot when I’m talking in Japanese. I’m doing that almost subconsciously to give back-channel feedback.
You can say そうですか (Is that so?) to ask back what you have just heard.
そうです can also be used with a verb/adjective "stem" or a "plain form" to convey additional meanings.
“Stem” + そうです expresses what you surmise.
あめがふりそうです。(It seems it’s going to rain.)
今日は遅れそうです。(I’m likely to be late today.)
このケーキはおいしそうです。(This cake looks delicious.)
このみずうみはとてもしずかそうです。(This lake looks very quiet.)
“Plain form” + そうです is used to convey what you have heard from somebody else.
あめがふるそうです。(I hear it’s going to rain.)
今日は遅れるそうです。(I hear [someone mentioned before] will be late today.)
このケーキはおいしいそうです。(I hear this cake is delicious.)
このみずうみはとてもしずかだそうです。(I hear this lake is very quiet.)
Of course, what you have heard can be something in the past and/or something in the negative form.
あめはふらないそうです。(I hear it’s not going to rain.)
あの人は昨日も遅れたそうです。(I hear he was late yesterday also.)
このケーキはおいしくないそうです。(I hear this cake is not delicious.)
このみずうみはしずかじゃなかったそうです。(I hear this lake was not quiet.)
