。
She's two years older than you.
Literal
She [topic-は] you [than-より] two years-older is.
より marks the standard of comparison ('than X'), while ２つ年上 stacks the native counter ~つ (used here with quantities-of-years differences) onto 年上 ('older'). Note that for absolute ages Japanese uses the counter 歳/才 ('years old'), but for differences in age, ~つ is common: 私より2つ上 ('two years older than me'). 年下 covers the opposite pole. Plain copula だ at the end keeps the register casual and confident.