This indicates to the individual that you are listening and being sympathetic with them. A simple slant of the head expresses you are willing to hear what they have to say. We can narrow our eyes, or open them wide. Eyes can even dance when we are amused or having fun. Your eyes can reflect how the other person's emotions are and validate their feelings without even saying a word.
Eyebrows are also part of our eye expressions and can accent the feelings expressed.
When seated across from someone, take note of their total body position. Remember, mirroring is a reflection of the other individual, not imitation. You want to be natural, not forced. Begin with a slight shift of your body. Gradually position feet and legs.