I have breakfast at 8 a.m. But my brother attends school at 7 a.m. and learns the lessons with his classmates. At school, he plays with his friends. After that, he returns home to ride his bicycle.
Sentence 2: The predicate (main verb) is "attends", which is third person singular. Who attends? ="My brother" is a noun used as a subject, and it is third person singular. The subject and verb in this sentence agree.
Sentence 3: The first predicate is "plays", which is also third person singular. Who attends? = "he" is a pronoun used as a subject, and it is third person singular masculine. Its antecedent is the noun "brother" in sentence 2, which is also third person singular. Therefore, the pronoun and its antecedent agree.