Think about a book resting on a table. The weight of the book pushes down on the table with a force of 2 N. How much force does the table put on the book?
The force that the book exerts on the table is a normal force, not a weight force. (The book's weight doesn't act on the table, it acts on the book.) It's equal in magnitude to the weight of the book, again, because of the first law.
