It refers to a skin type wherein there are more numbers of sebaceous glands around nose than other areas of the face, resulting in an oily T-zone, viz. forehead, nose and chin with dryness in other areas of the face.
In other words, the face is a combination of dryand oily skin
in different skin zones.
This is the most common skin type, and people with combination skin should consider using different products for different areas of the face to keep the skin balanced.
You may want to use a mild cleanser
Moisturizer on your cheeks
A more stringent product on your T-zone to cut through the oil