A good manager holds weekly good 1:1s with everyone in their team.
A good manager knows the strengths and weaknesses of their team members, and actively helps their team members grow and advance their careers.
A good manager understands that honesty creates trust, and that the responsibilities of a line manager, while partially overlapping, are not identical to the responsibilities of a friend.
A good manager does not delay having a difficult conversation when one is needed.
A good manager knows how to hire good people and how to let people go correctly.
A good engineering manager is a good engineer, and leads by example.
A good manager understands the work of their team well enough to support educated decisions.
A good manager is able to communicate effectively, and align their team with the vision, mission, and values of the company.