The core activity of Hager Group cannot be directly derived from the provided text, as it is a list of countries and languages in which the company operates. However, there are indications that Hager Group is a global company with a strong presence in various regions of the world. Based on the Hager Group website (not directly included in the provided text, but easily found), it can be concluded that the company's core activity lies in the development, manufacture, and distribution of electrical installation and distribution systems, switches, sockets, and other electrical components. Hager Group is a leading company in the electrical industry and offers a wide range of products and solutions for commercial, industrial, and private applications.