Subject pronouns are used to replace the subject of a sentence (the person or thing that is doing the action).
Here are some examples of subject pronouns in Spanish:
* yo (I)
* tú (you, informal)
* él (he)
* ella (she)
* nosotros (we)
* vosotros (you, plural, informal)
* ellos (they, masculine)
* ellas (they, feminine)
If you're referring to a brother as the subject of a sentence, you would use the appropriate pronoun based on the gender and number of the brother. For example:
* Él es mi hermano. (He is my brother.)
* Ella es mi hermana. (She is my sister.)
* Ellos son mis hermanos. (They are my brothers.)
* Ellas son mis hermanas. (They are my sisters.)