The term "roll your eyes" is used to indicate a degree of exasperation at someone's behaviour.
"When John heard that Isobel had fallen off her chair again, he rolled his eyes and laughed."
Using the smilie can be a way of showing that wither you understand you have made a mistake or indicating to someone else that you are not really agreeing with them. Those are my interpretations, anyhow.
Student or Learner