The Quran

وَمَريَمَ ابنَتَ عِمرانَ الَّتي أَحصَنَت فَرجَها فَنَفَخنا فيهِ مِن روحِنا وَصَدَّقَت بِكَلِماتِ رَبِّها وَكُتُبِهِ وَكانَت مِنَ القانِتينَ

Muhammad Asad

And [We have propounded yet another parable of God-consciousness in the story of] Mary, the daughter of Imran,¹ who guarded her chastity, whereupon We breathed of Our spirit into that [which was in her womb],² and who accepted the truth of her Sustainer's words - and [thus,] of His revelations³ - and was one of the truly devout.

I.e., a descendant of the House of 'lmran (cf. the last third of note 22 on 3:33).
I.e., into the as yet unborn child (Razi, thus explaining the pronoun in fihi). For an explanation of the much-misunderstood allegorical phrase, "We breathed of Our spirit into it", see note 87 on 21:91.
For the meaning of God's "words" (kalimat), see note 28 on 3:39.