。
She pictured city life in her mind.
Literal
She [topic-は] city [possessive-の] life [object-を] heart [in-に] depicted.
心に描く ('to depict in one's heart/mind') is a poetic expression for imagining or envisioning something. 心 here means 'mind' rather than 'heart' in the physical sense. 都会 ('the city / urban area') contrasts with 田舎 ('countryside') — a common binary in Japanese discussions of lifestyle.