If you have combination skin it means that your skin type features two or more different skin types on your face and the condition of your skin may change in different environments and in different seasons.
Typically it will be characterised by dryer skin on the cheeks and oily skin across the forehead, nose and chin, though it may also be a combination of oily and sensitive or dry and sensitive.
It will mean that you may need to find products that work across both skin types or you may need to use products only on specific parts of your face.