The Cooling Quality result indicates this area of the part has a cooling time variance which is greater than normal.
The Cooling Quality analysis calculates the entire time that is needed for all areas of the part to completely cool, and plots variations from that time value. When a result indicates that an area has a greater cooling time than normal, that area will require more cooling to compensate for the heat that is concentrated in that area.
When the cooling time variant is greater than normal, it can also indicate that you have big thickness variations in your part and that you should consider moving the gate into thicker rather than thinner areas.