Ben kitap okuyorum.
English: I am reading a book.
Subject-verb agreement in Turkish ('özne-yüklem uyumu') means that the verb (yüklem) must match the subject (özne) in person and number.
You use subject-verb agreement in every Turkish sentence where there is a subject and a verb. The verb ending must show who is doing the action and if it is singular or plural.
Ben kitap okuyorum.
English: I am reading a book.
Sen hızlı koşuyorsun.
English: You are running fast.
O yemek yapıyor.
English: He/She is cooking.
Biz film izliyoruz.
English: We are watching a movie.
Onlar parkta oynuyorlar.
English: They are playing in the park.