这是个主语从句句式，意思是“重要的是……”

这种类型很常见，举例说明：

1.What is important is that we have started, and we can begin to move forward in an object-oriented perspective.重要的是我们已经起步了，而且我们能够按照面向对象的方法一步一步的取得进展。

2.What is important is that you achieve a comprehensive expression of the solution approach you will eventually implement.重要的是要对你最终实现的解决方案完成一个全面的表述。

3.What is important is that, in my heart, I have a deep love for life. I will keep in high spirits.重要的是自己心中始终有一种对生活的热爱，始终保持积极上进的精神。