。
She is older than Tom.
Literal
She [topic-は] Tom [than-より] year-above is.
より marks the standard of comparison ('older than Tom'). 年上 / 年下 — literally 'above/below in years' — are the standard way Japanese expresses age difference, treating age as a vertical hierarchy. This vertical mapping carries social weight: お姉さん, 先輩, 弟 all encode relative seniority, and Japanese conversation often acknowledges the difference through honorifics and word choice rather than ignoring it.