Improved introduction of getter and setter (#22337)

Mentioned the principle of data encapsulation

guide/english/java/getters-and-setters/index.md

@@ -3,7 +3,7 @@ title: Getters & Setters
 ---
 
 # Getters & Setters
-Getters and Setters are used to effectively protect your data, particularly when creating classes. For each instance variable, a getter method returns its value while a setter method sets or updates its value. Getters and setters are also known as accessors and mutators, respectively.
+Getters and Setters are used to implement the principle of encapsulation and so the instance variable can be accessed only by its getter and setter methods. For each instance variable, a getter method returns its value while a setter method sets or updates its value. Getters and setters are also known as accessors and mutators, respectively.
 
 By convention, getters start with `get`, followed by the variable name, with the first letter of the variable name capitalized. Setters start with `set`, followed by the variable name, with the first letter of the variable name capitalized.