Gemütlichkeit is another word to learn.

If you come to Germany you can take part in any conversations just knowing genau and ach so.

Genau - Exactly, I understand, I agree. Used to express agreement. Germans like to agree. Use freely in any conversation at any time. Ach so - really, I see. Can be used to express agreement, astonishment, realization, understanding, questioning depending on intonation and stress. Na - hello, how are you, hey. Can be used at any time to start or avoid a conversation.