Complex sentence: He was then subsequently loaned out to Fortuna Sittard for the 2000--01 season where he made 21 league appearances while scoring once.
Split into simpler sentences: He was then subsequently loaned out to Fortuna Sittard for the duration of one season. He spent the 2000/01 season on loan to Fortuna Sittard where he made 21 league appearances while scoring once.