Leave room to think
Silence can be part of an attentive conversation.
In conversation
A pause does not always mean that a question has failed. The person may be recalling a situation or deciding how to explain it.
Notice the urge to answer your own question. Adding several alternatives can change what the speaker thinks you want to hear.
Give the conversation enough space, then clarify if needed. The aim is not silence for its own sake but an answer the speaker can own.