A reel is a tool used to store elongated and flexible objects (e.g. yarns/cords, ribbons, cables, hoses, etc.)
A so-called "two-reeler" would have run about 15–24 minutes since the actual short film shipped to a movie theater for exhibition may have had slightly less (but rarely more) than 1,000 ft (305 m) on it.
It runs, at sound speed, approximately the same amount of time (11–12 minutes) as a 1,000-foot (305 m) 35 mm reel.
In the silent era, the term was used to describe a single reel that accommodated two or more individual titles.
A showreel or demo reel is a short film showcasing a person's or organization's previous work.