Being labelled free range means that the operation has reached a standard set by a number of different accreditors or policy makers.
It can be about enabling the birds to have more freedom and express more innate behaviours (what are chickens innate behaviours?) or at least it will mean they will be able to stretch their wings outside some of the time in their lives.
There are a number of accreditors who set standards to be reached for definition of free range. There are a number of definitions of what free range chicken keeping is with different groups setting different standards. For example, The Soil Association, the EU organic, freedom foods, all set their own welfare standards. Certain operations may have even better conditions than minimum legal requirements for their particular label.
There are a number of things to look out for. How much freedom the birds have will depend on the design of the system, the quality of the yard (:outdoor habitat), the size of the pop holes, the proportion of the chicken’s life with access to the out side, the density of birds in one barn ( chicken density) , and the quality of the barn.
However generally there will be a barn and a range which, as the chickens reach a certain age, the birds will live in . There will be holes for the chickens to go in and out of which will likely be closed at night to help protect the birds from predators. Other systems, generally small scale ones, may have not have this.
There is a pressure to try and produce chickens as economically as possible. As such it often makes sense for farmers to push up to the limits of the standards they are aiming for. However a lot of producers would like to be able to aim higher, or to just make small changes that would affect the lives of the birds. However without consumer demand for these extra improvements the extra effort will count as loss. Increase in the value of the system needs to be advertised to increase the value of the product. There is pressure to try and produce food people need in the worlds and to try and produce as much of it as efficiently as possible. However as the consumers experience of such conditions becomes more and more distant the natural urge to care about the lives of chickens can be more easily ignored.