You've seen the word static on every method so far. A static method belongs to the class itself, not to any particular object created from that class. You call it using the class name: Math.sqrt(25) calls the static sqrt method on the Math class.
Since you haven't learned about objects yet, every method you write needs to be static. A static method can only access other static methods and static variables directly. It cannot reference non-static members without creating an object first.
Once you reach the OOP section, you'll see methods without static. Those are instance methods, and they operate on the data of a specific object.