Partial Dependency is one of the kind of functional dependency that occurs when primary key must be the candidate key and non prime attribute those depens on the subset/part of candidates key (i.e more than one primary key).
So try to understand partial dependency by following example :
Seller(Id, Product, Price)
Candidate Key : Id, ProductNon prime attribute : Price
Here Price attribute only depends on Product attribute which is a subset of candidate key,But Not the whole candidate key(Id, Product).It is called partial dependency.
So Product->Price is partial dependency.