What does 'public static void' mean in Java?

The public keyword is an access specifier, which allows the programmer to control the visibility of class members. When a class member is preceded by public, then that member may be accessed by code outside the class in which it is declared. (The opposite of public is private, which prevents a member from being used by code defined outside of its class.)

In this case, main( ) must be declared as public, since it must be called by code outside of its class when the program is started.

The keyword static allows main( ) to be called without having to instantiate a particular instance of the class. This is necessary since main( ) is called by the Java interpreter before any objects are made.

The keyword void simply tells the compiler that main( ) does not return a value. As you will see, methods may also return values.

It's three completely different things:

public means that the method is visible and can be called from other objects of other types. Other alternatives are private, protected, package and package-private. See here for more details.

static means that the method is associated with the class, not a specific instance (object) of that class. This means that you can call a static method without creating an object of the class.

void means that the method has no return value. If the method returned an int you would write int instead of void.

The combination of all three of these is most commonly seen on the main method which most tutorials will include.

The three words have orthogonal meanings.

public means that the method will be visible from classes in other packages.

static means that the method is not attached to a specific instance, and it has no "this". It is more or less a function.

void is the return type. It means "this method returns nothing".