The obligation to light Shabbat candles is rabbinic (not Torah law) but ancient, discussed across tractate Shabbat of the Talmud. The blessing wording is from the Geonic period (~7th-10th c.). The rabbis tied the obligation primarily to women because of a midrash on Eve: the first woman "extinguished the candle of the world" (by causing the expulsion from Eden), so women are given the privilege of re-kindling the light of the world every week.
The Ten Commandments appear twice in the Torah, once in Exodus and once in Deuteronomy. The two versions differ slightly on the Shabbat commandment: Exodus says zachor ("remember"); Deuteronomy says shamor ("keep"). The rabbis say both words were spoken simultaneously by God (a divine paradox), and the two candles represent these two commands woven together.
Many families add candles for each child, each guest, or each family member. The minimum is two; there is no maximum.
After saying the blessing and uncovering the eyes, many women take a quiet moment to add a personal prayer, for the family, for the children, for the week ahead, for whatever is heavy on the heart. This is one of the most cherished silent moments in the Jewish week. There is no fixed text, it is private, spontaneous, intimate. Some women cry into the candlelight. Some smile. Either is right.
For Sephardim and Mizrahi communities, the candles are sometimes lit at the table where the meal will be eaten; for Ashkenazim, often on a sideboard or a dedicated candle-area. Local custom varies. The blessing text is identical.