No vio a mi hermana y le golpeó con la puerta. He didn't see my sister and he hit her with the door.
Leísmo, Laísmo y Loísmo
There's three phenomena called "el leísmo, el laísmo y el loísmo" which are a very common mistake amongst native speakers. El leísmo is the misuse of the indirect object pronoun in place of the direct object pronoun. El laísmo is the misuse of the direct object pronoun (feminine) in place of the indirect object pronoun. El loísmo is the misuse of the direct object pronoun (masculine) in place of the indirect object pronoun. We'll get into more detail in a following lesson.