Of course, you can just say “yes” if you agree to something or want to give a positive reply. But did you know that there are other ways of saying “yes”?
Informal ways include: Yep, Sure, You bet, Sounds good, OK.
Formal ways include: Certainly, Of course, Definitely, Absolutely.
Sarcastic ways include: Yeah, yeah, yeah and Obviously.
Or you can just use sounds like Mhmm or Uh-huh.
However, I have to point out that you should always be careful when using gestures in other cultures. They can mean something totally different.