A Direct Object pronoun is a noun or pronoun that receives the verb's action.
Yo pateo la pelota.
(I kick the ball)
Yo la pateo
(I kick it)
Yo=subject; pateo=verb; la pelota=direct object.
Notice how the direct object pronoun in Spanish is placed between the subject and the main verb.
The following chart shows the correspondent object pronoun for each personal pronoun.