Objective / Accusative Case

A noun or pronoun is in the objective case when it is used as a direct object, an indirect object, or an object.
A noun which is directly affected by the action of a verb is put into the objective case. In English we call this noun the "direct object" which is a little more descriptive of its function. It's the direct object of some action.
  • Robert fixed the car.
In the example above, the "car" is in the objective case because it's the direct object of Robert's action of fixing. 

Personal Pronoun

Referring to the object in a sentence
 
Me
You
Him
Her
It
Us
Them
Whom
For example:
  • The web site gave Lynne a headache.
  • Mum gave us the money.
  • She gave him the book.