In simple terms, if you call a method that returns a value(which looks like this)
public int number()
int x = 5;
and this method above returns an 'int' type. A method that returns a value must use the keyword: "return". and whatever follows the return statement must correspond with what you wrote in the method declaration.
This example says 'int' in the declaration, but you can change it to any primitive, or any object, including boolean, String, etc.
If you would call that method, whatever is returned (in this case x = 5, which is 5) is replaced by the call to the method.
is like saying