People learn more freely around someone who does not make ignorance embarrassing.

Admitting you do not know something is the entry cost of learning, and people will not pay it in a place where not knowing is treated as a failure. So they nod, stay quiet, and remain stuck. Making ignorance unembarrassing costs nothing and multiplies how much learning actually happens around you.

Say plainly when you do not know something. Respond to questions as though they were reasonable, because they were. The atmosphere you create determines what people are willing to ask.