Complex sentence: Halfdan (Heimskringla and Rolf Krake's saga) or Healfdene (Beowulf) was a mythological king of Denmark of the House of Shieldings and the son of king Frode.
Split into simpler sentences: Halfdan (Heimskringla and Rolf Krake's saga) or Healfdene (Beowulf). He was a mythological king of Denmark of the House of Shieldings and the son of king Frode.