Complex sentence: Coughlin most recently served as the head coach for the New York Giants, a position he served in for 12 seasons, where he led the Giants to victory in Super Bowl XLII and Super Bowl XLVI.
Split into simpler sentences: Coughlin most recently served as the head coach for the New York Giants, a position he served in for 12 seasons. Coughlin led the Giants to victory in Super Bowl XLII and Super Bowl XLVI.