This is a person's exclusive right to publish and sell, literary musical or artistic work. i think this is an amendment

The word you are looking for is "copyright."  It is not in an amendment, but the Constitution does give Congress the right to make laws to protect these.  The Constitution does this in Article I, Section 8, Clause 8.

The reason this is important enough to be in the Constitution is that it is a right that is vital to have if you want your economy to be strong.  If people can copyright their works, they will be more likely to write books, songs, (nowadays this includes movies and software and stuff like that).  Otherwise, they will not want to do that because they'll do all the hard work and then someone else will come in and get the money.