The word for which the pronoun stands is called its antecedent. It may be in the same sentence, in a previous sentence, or not given at all. An example would be The boy threw the football. He threw it over the fence. Boy is the antecedent for he, and football is the antecedent for it. A pronoun can be an antecedent for another pronoun. He likes his new car. He is the antecedent for his. The antecedent always comes before the pronoun for which it is the antecedent.
Pick out the pronouns and their antecedents in these sentences.
1. He ran after his dad.
2. Jennie wanted her doll for bedtime.
3. The rabbit hopped into its hole.
4. They will help you with your work themselves.
5. The teacher gave us homework everyday, and she made our lives miserable.
Answers

1. He is the antecedent for his.
2. Jennie is the antecedent for her.
3. Rabbit is the antecedent for its.
4. They is the antecedent for themselves, and you is the antecedent for your.
5. Teacher is the antecedent for she, and us is the antecedent for our.