Complex sentence: The album debuted atop the U.S. "Billboard" 200 with first-week sales of 346,000 copies, becoming her second non-consecutive number one album (after her 1999 self-titled debut album) and the best-selling debut week of her career.
Split into simpler sentences: The album debuted atop the US "Billboard" 200 with first-week sales of 346,000 copies. Consequentially, it became her second non-consecutive number one album after her debut release "Christina Aguilera" (1999) and the best-selling debut week of her career.