If what the person is saying is not very clear to us, we can ask more questions to try and understand them. For instance, we can say: "Can you explain this please?"
Asking questions also shows the other person that we are interested to know more about them and their problem. Of course, make sure never to ask questions to satisfy your own curiosity. Questions are asked to understand how we can help better.
It is best to ask questions the answers to which are not just one word and the person has to give an explanation. These are called open-ended questions. If we ask someone: "What happened to you?" Naturally they will have to explain what is upsetting them or what has happened in a few sentences. This gives us time to establish a better connection by listening, with our nonverbal behavior, and other communication skills. But if we ask: "Has something happened?" They might say: "No!" Or "Yes!" Or just shake their head. Then, we have to repeat our question differently to understand what has happened.
Questions to which the answer is very short, or just a yes or no, are called close-ended questions. Sometimes we have to use close-ended questions. But, overall, it is best to ask a larger number of open-ended questions than close-ended questions. Please note that a “no” by the other person means that they are currently not willing to talk. If so, we must respect their wish and not bother them with more questions.