what is the purpose of substring in java code example

Example: how to do substring java

class Main {
  public static void main (String[] args) {
    
    String str = "Hello World!";
    
    String firstWord = str.substring(0, 5);
    //two parameters are start and end index: (inclusive, non-inclusive)
    
    String secondWord = str.substring(6, 11);
    
    //firstWord has string "Hello"
    //secondWord has string "World"
  }
}