System.out.println() in Java?

System is the class available in java.lang package. see the System class structure below
public final class System {
}


out is static field of System class . out is a static field so we can call by System.out which means classname.field see below snippet
public final class System {
 public final static PrintStream out = null;
//more code 
}
println is a method of java.io.PrintStream. This method is used to print message to console. See the snippet below
public class PrintStream extends FilterOutputStream
    implements Appendable, Closeable
{
//morecode
public void println() {
//more code
        
    }
Example
package com.practice;

public class Demo {
 // main method
 public static void main(String[] args) {

  System.out.println("welcome to java tutorials");

 }

}
Output