The significance of this case was that it set up a way of legal reasoning that would allow the creation of labor unions. This case helped to make it more possible for labor unions to exist in the US.
Before this case, American law followed British law in thinking of unions as illegal groups. They were seen as conspiracies that affected the rights of workers and employers to make contracts with one another. This was a matter of common law (made through court cases) not of statutory law (made by legislatures). In Commonwealth v. Hunt, the court rejected this line of reasoning and held, instead, that unions were legal so long as they did not either A) try to accomplish an illegal goal or B) try to accomplish a legal goal by illegal means.