For a more formal description, you can read the BOE Policy Manual, Bylaws Section 0120. (I'm not going to put a link here because I'm not sure you want to download the 1,633-page document.)
When I sense that someone may have a misconception about what the BOE does, I try to get across two main (helpful) facts:
1) The Board of Education does not run the schools. The Board's job is to make sure the schools are well run.
2) Any single BOE member has absolutely no power or authority, except when acting, by vote, as a member of the five-member Board.
Both of those facts come from the New Jersey statute 18A, which also states that every Board member must all make decisions "based on the educational welfare of children."
Last year I ran across this quote regarding micromanaging by Boards of Ed. It's a helpful perspective:
Democracy does not mean that the people’s representatives — the school board—take over and operate the schools any more than it means that the board members of a symphony play the violins.An interesting way to put it, but makes sense.
-- American School Board Journal, November 2010