When the User hover over a component of a Visual such as pie or a bar or a point, if the mouse cursor turns to a hand cursor, it means the component can be clicked to see more detailed information.
Such detailed Information can be in the form of a drilled down Visual or a list of information in the form of a table.
For example, clicking on the part of a Bar in the below Visual, opens up a Pie with the details of the selected Bar.
