Body language shows you are listening. You can also send the message that you're not listening by the way you sit or stand. Slouching in your chair and looking around the room can make the speaker think you're bored. Instead, sit up straight, facing the speaker. Maintain eye contact while listening, and lean forward to show you're engaged in what's being said.
Paraphrasing what you hear is restating it in your own words. Paraphrasing in conversation shows you have listened to what was said, and processed it to be able to express it in your own words. Summarizing brings what was said together to find a main idea or key points. This is how you show that you understand what the speaker was talking about, and what was important in what was said. Paraphrasing and summarizing express that you understand what was said to you.
Clarifying helps you better understand anything that was said that's unclear. It provides more information, ensures you have the right interpretation, and can help the speaker see other points of view. If you're not sure about something that was said, getting clarification will keep you from a misunderstanding. Clarifying shows you were listening because you've been able to identify things you don't fully understand.
Empathy is how you show you understand what the speaker is feeling or going through. This goes beyond understanding what's said and shows you're relating to the speaker's experience. Acknowledging the speaker's feelings also helps you engage her during the conversation. It shows that you care about the speaker as a person as much as you care about what she is saying.