"Jein" is definitely one of the best words in the German language.
It's one word for both yes and no.
ja + nein = jein
Knowing the word "jein" in German opens up a whole new world for German learners and their eyes get really big and their ears perk the first time they hear the word.
"Jein" also has several uses; for starters, "jein" allows you to give two simultaneous answers to one question: ja und nein - yes and no.
This is perfect for difficult answers.
When it's impossible to give a simple answer to a question, "jein" signals that your response can't be summed up in one sentence and that your listener needs to pay attention to your entire response.
"Jein" is also a great response when you are still undecided yourself. "Jein," you want to move to a bigger apartment (ja, umziehen!), but your commute to work is so short now (nein, nicht umziehen!), however you need a bit more space (ja, umziehen!), but you don't know yet how much more space you want (nein, nicht umziehen!).
So when you have multiple answers to a question, remember you can rely on "jein" to signal a multi-layered response.
Viel Spaß damit!