The phrase "city kind hearts" can be interpreted in a few different ways, but generally it refers to people in urban areas who are compassionate and caring. Synonyms for this phrase might include "urban benevolence," "metropolitan empathy," or "city compassion." Other phrases that could convey a similar meaning might include "community kindness," "localized altruism," or "compassionate city dwellers." Ultimately, the goal is to find language that encapsulates the idea of caring, supportive people living in an urban environment. Many different phrases and synonyms could achieve this aim, depending on the context and the specific connotations that you're trying to convey.