The phrase "heart and soul" is an idiomatic expression that means with complete dedication, devotion or enthusiasm. It implies putting in maximum effort and being fully committed to something, showing great passion and intensity towards it. The phrase suggests that a person's emotions and inner feelings are completely involved in the task at hand, leaving no room for half-hearted efforts or lack of interest. In essence, "heart and soul" means giving your all to something, putting everything you have into it, and truly believing in its importance.