What is the origin of the idiom "heads will roll" and when to use it?

The origin of the idiom "heads will roll" is unclear, but it is believed to have originated in medieval times when the heads of executed prisoners were displayed on spikes as a warning to others. It has been used in English since at least the early 20th century. This phrase is used to describe a situation where people will be punished or held accountable for a problem or failure.