all-night service; overnight operation
Refers to transportation or facilities running through the night, such as trains, buses, or customer service lines.
On New Year's Eve, the subway runs all night.
終夜 alone means 'all night' as an adverb or noun, while 終夜運転 specifically refers to all-night operation of a service.
Compound of 終夜 (all night) and 運転 (operation, driving).