A derived class can inherit from one or more base classes.
This leads to single and multiple inheritance.
A sofa-bed is a sofa and it is also a bed.
Both are items of furniture.
This might lead to a base class for Furniture and two derived classes for Sofa and Bed, each derived from Furniture.
This might then lead to another multiply derived class, Sofabed, which is derived from both Sofa and from Bed - multiple inheritance.