。
She gave me a watch as a birthday present.
Literal
She [topic-は] me [to-に] birthday's gift [as-として] watch [object-を] gave.
~として marks the role or capacity in which something serves — here, the watch is given 'in the capacity of' a birthday gift. The pattern is highly productive: 友達として ('as a friend'), 教師として ('as a teacher'), プレゼントとして ('as a present'). Note how Japanese front-loads the framing (誕生日の贈り物として) before naming the actual object (時計) — a structural mirror of how categories tend to precede instances in Japanese, the opposite of English's 'a watch as a birthday gift.'