"Right to work" refers to the "right" that workers have to be emploed without joining a union.

The states that have laws against union membership as a condition of employment are Alabama, Arizona, Arkansas, Florida, Georgia, Idaho, Indiana, Iowa, Kansas, Kentucky, Louisiana, Michigan, Mississippi, Nebraska, Nevada, North Carolina, North Dakota, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, West Virginia, Wisconsin, and Wyoming.

In these states, if a union has presence in a workplace, you are not required to be a member of that union to be employed there. This can mean that your compensation, benefits, work hours, overtime availability, rest hours, safety considerations, etc., are different from (read: worse than) the union member next to you doing the exact same work.

Obviously, the emplyer isn't going to make those things too much worse, else they would drive more of their workers into the union, which means that even non-union workers in a workplace where a union operates benefit from that union, and they receive that benefit for free.

Thank you, unions.