What's the meaning of "twenty----four seven"?

Meaning：

All of the time - twenty four hours/day and seven days/week.





Origin：

This American term was coined as black street-slang in the early 1980s and soon became adopted as a noun by various sectors of society. The earliest example that I can find of it in print is the November 1983 edition of Sports Illustrated:

Jerry (Ice) Reynolds, one of the SEC's two best freshmen by the end of last season, calls his jump shot '24-7-365', because 'It's good 24 hours a day, seven days a week, 365 days a year'.