can somebody explain this code step by step please ?

I mainly don't understand the part While (s.empty)

List L (7,4,8,2,5,3,9) Priority Queue P Input sequence s, comparat Lemen Output sequence s (sorted in increa rder ording Input Phase (a)(4,8,2,5,3,9) Algorithm PQ-Sort (S, C) P-priority queue with comparator C while (S.empty)) (4,7) (4,7,8) (2,4,7,8) (2,4,5,7,8) (2,3,4,5,7,8) (2,3,4,5,7,8,9) (3,4,5,7,8,9) (4,5,7,8,9) (b)(8,2,5,3,9) (c)(2,5,3,9) (d)(5,3,9) e5.front (); S.eraseFront () P.insert (e); (3,9) Phase 2 (a) while (P.empty)) eP.min); P.removeMin () S.insertBack (e); (2,3) (g) (2,3,4,5,7,8,9)