Bylaws are rules about what can and can’t be done in the Forest. Forestry England and the National Trust each have byelaws for the parts of the Forest they own or manage.
The Verderer’s byelaws apply across the Forest, and are mainly about commoning- for example, there’s a rule that ponies living out on the Forest can’t be shod. The bylaws are there to protect the Forest, so get to know them. You can download the Verderers’ byelaws here.