This he said, signifying what death he should die. (This he said, signifying what death, х poioo (G4169) thanatoo (G2288) rather, 'what kind' or 'manner of death'] he should die)-that is, His being "lifted up from the earth" was meant to signify His being uplifted on the accursed tree (John 3:14; John 8:28).
Related Commentaries of John 12:33
John 12:33
33 This he said, signifying what death he should die.