reduced business hours; shortened operating hours
Refers to a business or facility operating with shorter hours than usual, often due to external circumstances like pandemic measures or energy saving.
During the state of emergency, many restaurants were forced to operate under reduced hours.
This supermarket is operating on shortened hours until 8 p.m.
時間短縮 is the full phrase meaning 'time reduction' in general; 時短 is its abbreviation and often appears in compounds like 時短営業.
営業時間 simply means 'business hours'; 時短営業 specifically implies those hours have been reduced from the norm.
Compound of 時短 (jitan), an abbreviation of 時間短縮 (jikan tanshuku, 'time reduction'), and 営業 (eigyō, 'business operations').