What is "public static void "mean and use for?

Answer 1

I think you are referring to the public static void main. Thus is the method where your java program starts when you run it. From there you start everything elss

Answer 2

relating with "public static void main" since main method is called by jvm. so public denotes that it can be access from outside. statics denotes that we don't need to create an object. it can be called by classname. by means the method returns with no value.