What is a mentor exactly?

Experience is valuable. You can gain experience by doing stuff yourself, getting it wrong, and learning. Alternatively, you can just ask someone with more experience. So, a mentor is a someone who guides you as a manager. They're probably older than you. They might have a mentor of their own. You might have a mentee of your own.

There's no clear best way of doing it. You might have just one or a few mentors, or many of them.

• With a few mentors, you get a fairly narrow point of view, but they will know a lot about you. The nice thing about them knowing you well is that their advice will be less generic and more applicable to you.
• With a lot of mentors, you get a number of points of view, but they will not know you that well. The nice thing about getting lots of data points is that you can average out any biases they may have.

When you receive advice from those with experience, or a different perspective - it probably won't be rocket science, but it will help force clarity in your thinking.