Frustration clicks are triggered when a user repeatedly clicks on the same are of the page.
Here is an example, let's say the burger menu on your mobile site breaks witha new release. You will soon start noticing frustration clicks on it in Browsee, indicating that the element is not responding when user's click on it.
Most frustration clicks are signs of broken functionality, incomplete or errenous JS errors or network errors.
However, there are times when frustration clicks are triggered on UI elements like image sliders. In these case you can, go to the User Experience tab and Mark As Resolved and Browsee will remember to not trigger a frustration click on that element.