補殺 is read as ほさつ (hosatsu) and means assist.
ほさつ
hosatsu
ほじょ
spotting (in weight training)
ほきょう
reinforcement
ほせい
correction
ほきゅう
supply
ほけつ
filling a vacancy
ほそく
supplement
おぎなう
to supplement
ほせいよさん
revised budget
ほかん
complementation
おぎない
replenishment
ほしゅう
supplementary lessons
ほどう
guidance