p = p.getNext();

Advancing the Pointer

The variable p can point to any Node. The statement...

 p = p.getNext();

...does this:

Step 1:  evaluate the right hand side
         p.getNext() evaluates to the pointer contained in the first Node

Step 2:  p = 
         that pointer is copied into p
         now p points to the second node.

The picture shows this.

This operation, moving a pointer from one Node to the next in a chain of Nodes is a common operation in data structures. It is called advancing the pointer.

 p = p.getNext();