。
She gave me a letter.
Literal
She [topic-は] me [to-に] letter [object-を] gave.
The minimal letter-giving sentence. Note that くれる here is for handing over a physical letter — distinct from 手紙を出す ('to mail/send a letter,' literally 'to put out a letter'), which involves the postal system. With くれる it's a personal hand-delivery; with 出す it's mailing. 送る also works for sending. These three verbs let you place the letter at different points along the journey from sender to recipient.