Used to state the main point or gist; 'in short', 'the point is', 'basically'. Frequently used in spoken language.
要は君が来たくないだけだよね？
Basically, you just don't want to come, right?
要は時間が足りないということだ。
In short, it means there's not enough time.
色々言ったけど、要はお金が必要だということだ。
I said a lot, but the point is that money is needed.
要は、準備不足が問題だったんだ。
The point is that lack of preparation was the problem.