The Right-to-Work law secures the right of employees to decide for themselves whether or not to join or financially support a union. Only certain states are right-to-work states, whereas others are still forced unionism states (see below).
Arizona, Nebraska, Nevada and Wyoming are right to work states, and employees have the right to decide whether or not they join and financially support a union. So, if a union were elected at your location, even if you never signed and never voted for the union, you are still represented by the union and therefore bound to any contract the union negotiates. However, you are not legally required to join or financially support the union. But be aware that some pro-union employees and union stewards have been known to pressure those employees to pay dues anyway.
California and Alaska are non-right to work, or forced unionism, states. Employees in these states are subject to the 'Union Security' clause of a union contract, which requires all employees to either join the union, or pay union dues as a condition of employment. So, those employees who object to union representation could legally be fired from their jobs if they chose not to join and financially support a union.
Colorado is a modified "Right to Work" state where bargaining unit employees cannot be required to join a union, but they can be required to financially support a union.