What does the term hit by a bus mean?

The term "hit by a bus" is often used metaphorically to describe an unexpected or sudden event that can drastically change a situation, particularly in the context of someone's sudden absence or unavailability. It suggests that someone could be incapacitated or removed from a role, typically without warning, leading to potential consequences for others involved. It underscores the importance of contingency planning in various scenariOS, such as business or project management.