Reading about how to be a good listener can only get someone so far - watching someone demonstrate it and talking about it is the surest way to understand what it means.
Specifically, Reflective listening[1], Clean language[2], and the approach used by Eugene Gendlin[3], jump-started my own skill of practicing being a good listener. You may also hear the term "holding space" as a sort of umbrella term for this as well.
You would be amazing at how far these go toward creating a safe, non-judgemental, space for people. Simple, open-ended, genuine questions worded in their own language, has afforded me the opportunity to hear people open up from the very bottom of their souls. It's absolutely amazing that the simple act of listening can do that, but it does.
1. https://en.wikipedia.org/wiki/Reflective_listening
2. https://en.wikipedia.org/wiki/Clean_language
3. Wiki reference, but best seen, of course, on Youtube https://en.wikipedia.org/wiki/Eugene_Gendlin