Complex sentence: It was the first imprint to identify a public entity called'Conceptual Art' and also the first to serve the theoretical and conversational interests of a community of artists and critics, who were its producers and users.
Split into simpler sentences: It was the first imprint to identify a public entity called'Conceptual Art'. The journal was the first to serve the theoretical and conversational interests of a community of artists and critics, who were also its producers and users.