A more thorough explanation:

A serjeant-at-arms, also spelled sergeant-at-arms, is an officer who serves various roles in different contexts.

In the past, a serjeant-at-arms was an armed officer who attended a sovereign, providing protection and security.

Example: In medieval times, the serjeant-at-arms would accompany the king on his travels and protect him from any threats.

In modern times, a serjeant-at-arms is an officer assigned by the Crown to attend a session of Parliament. They are responsible for maintaining order and serving notices and process on behalf of the legislative body and its committees.

Example: During a parliamentary session, the serjeant-at-arms may be called upon to remove a disruptive member of parliament or to deliver important documents to the speaker.

In parliamentary law, a serjeant-at-arms is an officer charged with helping keep order in a meeting under the chair's direction.

Example: During a meeting of a student council, the serjeant-at-arms may be responsible for ensuring that everyone follows the rules of order and that the meeting runs smoothly.

A serjeant-at-arms may also be referred to as a warden or warrant officer.