Translation:

24. Round about them will serve (devoted) to them youths (handsome) as Pearls well-guarded.

Notes (Tafseer)

5058. Maknun: well-guarded, kept close, concealed from exposure: the beautiful nacreous lustre of Pearls is disfigured by exposure to gases, vapours, or acids; when not actually in use they are best kept in closed caskets, guarded from deteriorating agencies.