她的心是一座城他是唯一的城民
[tā de xīn shì yī zuò chéng tā shì wéi yī de chéng mín]
In the sentence, she has a city-like heart, he's her only inhabitant. Her emotions, personality, or experiences are vast like a city while he represents something unique or significant enough within her world or emotional universe to stand alone. It illustrates deep connection, loyalty between two individuals.