Hi, Skyler! In short, FERPA is The Family Educational Rights and Privacy Act of 1974 - an act passed to protect the privacy of students' educational records. In waiving your right, you will not be able to access your letters of recommendation. It is important to note that these letters would only be accessible after you were accepted into that specific university - if you ultimately went to a different school, you would not be able to view them regardless of your choice. I've attached a link to an article that summarizes the act and provides a recommendation for what students should do.
Hope this helps and good luck in the application process!