One of best ways to show employees that you are listening is to ask them follow up questions with the Instant Feedback and Chat tools. Even if you do not have a perfect solution to an employee's comment, sending them a Chat saying you have read the comment and will do your best to help gives them confidence that their feedback isn't disappearing into a black hole.
53% of employees feel their leader is not doing a good job encouraging and recognizing suggestions for improvement  so these are great tools for you to stand out from the crowd.
When employees are unhappy but you're not sure how to improve their mood, request additional details through Instant Feedback!
Make sure to respond to all employee comments through Chat! At the minimum you should provide a simple acknowledgement.
 "Only 1 Out Of 4 Leaders Encourage Suggestions From Their Employees, New Data Shows". Mark Murphy, 22 October 2017.