i dont understand that in java ,please explain that

Organizing Classes public class Employee private int empNum private String empLastName; private String empFirstName; private double empSalary; public int getEmpNumO 131 return empNum public void setEmpNum (int emp) empNum-emp public String getEmpLastName O return empLastName; public void setEmpLastName (String name) empLastName name; public String getEmpFirstNameO return empFirstName public void setEmpFirstName(String name) empFirstNamename; public double getEmpSalaryO return empSalary; public void setEmpSalary(double sal) empSalarysal; Figure 3-22 The Employee class with several data fields and corresponding methods