Why aren't we using the traditional way of printing the data on console using System.out.println(); functions ?

I assume you are referring to the teachers use of the printf() method instead of println(). The reason is simple readability. Let's say I wanted to display text and include 3 variables which looked something like this:

System.out.println("My first variable is " + firstVar + " and then you get " + secondVar + " all while maintaining that " + third var +
" is also true.");
System.out.printf("My first variable is %s and then you get %s all while maintaining that %s is also true\n", firstVar, secondVar, 
thirdVar);

The printf command makes it look a lot nicer and simpler to read. There is nothing wrong with either one as they both work to do the same job. I myself only knew about the println until I began this course. If using variables, I now use the printf for simplicity.

You can do that too and you'll have to use it when you follow the Java course for a few minutes more than you did now ;)