It means that they open or start something at 5 o'clock at night and they go until their closing time.
5 pm
5 pm
5 pm
5 pm
5:30 pm
They open at 5 am and close at 11 pm
5 pm
5:30 pm
They most likely close on Saturdays.
They open at 5 am and close at 11 pm
COB = close of business usually by 5:00 pm
Close of Business. Eg. 5 pm