The simple subject is the main noun or pronoun that tells what the sentence is about.
1- The batter swung at the third ball. (main noun as simple subject)
2- She hit a high pop foul. (main pronoun as simple subject)
A simple predicate is the verb or verb phrase that expresses action or being about the
subject.
1- The crowd cheered after the touchdown. (main verb as simple predicate)
2- The team will practice on Saturday. (main verb phrase as simple predicate)