be of service
To be able to help or serve someone. The resident file clerk is here! How can I be of service?
be of service (to someone or something)
To help, serve, assist, or work for someone or some group or organization. Good evening, sir, how may I be of service? My father was of service to that company for over 50 years, and the only thing they gave him at the end was a cheap watch.
of service to someone, be
Help someone, as in How can I be of service to you? This idiom uses service in the sense of "supplying someone's needs." [c. 1700]
be of ˈservice (to somebody)
(formal) be helpful (to somebody): If I can be of service, please let me know. be of service
To be ready to help or be useful.