支署 is read as ししょ (shisho) and means substation.
ししょ
shisho
しはいてき
dominant
しちゅう
prop
しちょう
(governmental) branch office
しじだんたい
support group
しはいてきちい
driver's seat
ししゅつがく
(amount of) expenditures or disbursements
しじせん
support line
しせん
branch line
しじそう
base support (e.g. for a party in an election)
しじりょうほう
supportive care
しきゅうがく
allowance
しねんせい
combustibility