。
She's about the same age as me.
Literal
She [topic-は] me [as-と] same-amount of age is.
A nominal use of the equal-comparison frame X と同じくらい — instead of comparing how tall or how young, the noun 年齢 ('age') itself is the dimension. ~の年齢 lets 同じくらい modify the noun: 'an age of the same approximate amount as mine.' The polite copula です rounds out the predicate. This pattern is convenient when there's no single adjective for the property — Japanese doesn't have an exact adjective meaning 'aged X,' so it falls back on the nominal '~ of [property].'