This expression means to get to the bottom or most important part of something.

VOA: special.2010.05.16

And if you hang around, as I hope you will, we'll get to the bottom of some of them.

如果你喜欢这门课,我喜欢你们喜欢,我们会一点一点揭开他们

耶鲁公开课 - 1871年后的法国课程节选

There are widespread controversies about it, and many of the courses you would take in law school are meant to try to get to the bottom of these thorny questions.

这个问题有很多争议，法学院的很多课都旨在,把这些棘手的问题弄得水落石出。

耶鲁公开课 - 文学理论导论课程节选

You can kind of see where the syntax is going, looks like a loop, but you can kind of put blocks inside of you, and the little arrow suggests that once you get to the bottom just like our socks example, you're gonna do the following again.

从某种程度上你可以看到它的语法构成,像个循环，你也可以把，一些程序块放到循环中，如同短袜的例子，这个小箭头暗示你一旦到达底部,你将会重复接下来的事情。

哈佛公开课 - 计算机科学课程节选