If you're an investor, what do you like your startups to tell you?
If you're a founder, what do you like to report up to your board, and what do you like to discuss with them?
What are your "standard agenda items" besides acceptance of the minutes and votes on stock grants?
The real purpose is an assessment of product/market fit, customer adoption, product development and financial results. Each are taken up qualitatively and qualitatively based on an artifact (either memo or slides) created by the CEO and discussed during the meeting.
The CEO creates the agenda, proposes it to the board members who give feedback, then creates the artifact based around the agenda in order of importance. Discussion ensues about the artifact and how much progress is being made, how satisfying that is, and changes/decisions for the CEO to take in follow-up.
It's typically a discussion meeting rather than a decision meeting. It should force reflection and progress with the CEO contriving and making decisions about changes to make to financial, customer and product decisions in follow-up solo. Then the next meeting you check on what effect that had.