。
She is as young as I am.
Literal
She [topic-は] me [as-と] same-amount young.
A bare equal-comparison: she and I share the property of being young to the same degree. 若い is an i-adjective and forms its own predicate without a copula — 若い alone is a complete sentence (若いです in polite form). Note how compact Japanese can be: no copula needed, no overt subject for the property. The と同じくらい frame remains the workhorse for 'as...as' equal comparisons.