It is a section in the terms and conditions that says if you have a disagreement with the company over something in the contract and cannot resolve it with them informally, you may not sue. You may only take your dispute to a non-judge arbitrator, who is usually paid by the company you are arguing with and whose ruling you may not appeal. You also may not come together as a group with other people who are wronged and argue as a group; each of you must argue individually.

A series of articles with more information on why this is crap, especially for business-to-consumer take-it-or-leave-it contracts: https://www.nytimes.com/2015/11/01/business/dealbook/arbitra...