What is the use of "System.out::println" in Java 8 code example

Example: java system.out.println

System.out.print(<string>); //prints in the same line as the previous print
System.out.println(<string>); //prints in a new line

// Example
System.out.print("This ");
System.out.print("will ");
System.out.print("be ");
System.out.print("all ");
System.out.print("in ");
System.out.print("one ");
System.out.print("line.");

System.out.println("Hello World!");
System.out.println("second line");