An objective is something you plan to achieve. A military objective is the overall plan for a mission. The objective for a bake sale is to raise money. If your objective is to learn a new word, you have succeeded.
An objective is the point of something. If you don’t understand the objective of a class, then you don’t know what you were supposed to learn. The word itself is often used in business or work. Another meaning of objective is “looking at things in a detached, impartial, fact-based way.” If a police officer falls in love with a witness, it might be hard for her to stay objective. The word comes from the Latin ob "against" + jacere "to throw.”