The best way to let someone know that you understand and care about what they are saying is to

listen actively and attentively. Show empathy through your body language, such as nodding and making eye contact. Reflect back what they are saying by paraphrasing and summarizing their points to ensure you are understanding correctly. Ask follow-up questions to show interest and engage in the conversation. Offer emotional support and validation by acknowledging their feelings and experiences. Lastly, express your genuine concern and willingness to help or provide support in any way you can.