三死 is read as さんし (sanshi) and means three outs.
さんし
sanshi
さんぼう
small offering stand
さんしゃ
three persons
さんど
third (interval)
さんだい
third generation
さんもん
three one-mon coins
さんしょく
three colours
さんしゅん
three spring months
さんたい
The Three-Body Problem (2008 novel and subsequent adaptations)
せいし
death
びょうし
death from disease
にし
two out
し
(an) out