Answer:
“Hic iacet Arthurus, rex quondam rexque futurus” means “Here lies Arthur, the once and future king.”
Step-by-step explanation:
According to the book "Le Morte d'Arthur" the inscription “Hic iacet Arthurus, rex quondam rexque futurus” means “Here lies Arthur, the once and future king.” this inscription was written upon King Arthur's tomb according to this reference, This was used later as the title of T.H. White "The Once and Future King"