Catechism of the Catholic Church §1243 — excerpt
The white garment symbolizes that the person baptized has "put on Christ," has risen with Christ. the candle, lit from the Easter candle, signifies that Christ has enlightened the neophyte.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.