Companies have a board of directors to provide oversight, guidance, and advice. They're generally not involved in the day to day operations of the company, and are composed of people with different experiences and backgrounds, often from other industries. They work to advance the company, but are not beholden to it.
That's nice, but how is it relevant to a developer? It's relevant because the main role of a company's board is to help the company progress and grow. As a developer you want the same thing. You want career progression and growth. And that's why you should have a personal board of directors.
Now a personal board is much less formal than a corporate board. There are no articles of incorporation, the positions are unpaid, and often the people on the board don't know they're on it. Your board is a set of people who you trust to give you honest advice and help open doors for you.
So who goes on your personal board? The specific people are up to you, but there are a few roles you want to fill. You'll want at least one traditional mentor. Someone you can go to and actively seek advice and guidance. The person you go to when you have a particularly thorny problem you need to work through. And you might have more than one if you have different types of problems.
You'll want someone who knows people and can open doors for you. Someone who can provide introductions to the people you really need to talk to. Whatever it is you're doing, it probably impacts and involves other people/teams, and this person can get you in touch with the appropriate counterpart on the other side and facilitate the initial discussion. Again, you might have more than one of these depending on what you're doing.
You'll probably need someone who can get things done for you. Someone who, if you get them on board, will bring others with them. A force multiplier so that after you get them on board you can focus on something else. This board member is the most situational, as that kind of influence is often specific.
Finally, and surprisingly, you're going to want an honest critic. Someone who can be critical of what you're saying/doing, and do it in a way that provides clear, actionable feedback. This is the person who helps you say things not just in a way that can be understood, but in a way that can't be misunderstood. They point out the holes and flaws in your arguments and help you fix them.
Remember, you're responsible for your career, so you should do what you can to improve it. That starts by getting the help and advice you need.