What Is "To And From" In This Sentence?

Hi. I´m an interpreter and I can tell you that shadowing is very, very useful... For interpreters, that is. We use it to, simply put, pick up the rhythm of the speakers and to understand at what point do we need to start interpreting once the speaker begins his or her speech. I do shadowing every day, but that has nothing to do with learning a language. You guys need to understand that shadowing is already hard to do even in your native language. I´m fluent in the languages I interpret to and from, and shadowing is still challenging and certainly useless to try to improve my language skills. Doing shadowing when you are trying to learn a language is like lifting heavy things because you want to become really good at math, one thing has nothing to do with the other even if you feel you are making a great effort. So, take it from the guy that does shadowing every day, it doesn´t work for language learning.

---

The only thing/phrase above I can't understand/interpret perfectly is about to and from. Could you tell me what to and from means? Grammatically, it seems to be an adverb phrase. Dictionaries just contain not to and from but to and fro as in She rocked the baby to and fro.