What is the use of generating getters and setters in a class annotated with @Entity (Hibernate)?

What is the use of generating getters and setters in a class annotated with @Entity (Hibernate)?
When do they get invoked?

@Entity
@Table(name="student")
public class Student {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="id")
    private int id;
    private String firstName;
    private String lastName;
    public Student() {
    }

    public Student(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }

    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
//other getters and setters
}

>Solution :

As soon as your fields are private then you need getters and setters to access them outside of the entity class.