Bosses come in all shapes and sizes, and in widely differing skill levels. Some bosses are TMI; others laconic as clams. Some are naturally devious; others straightforward. Some honest; others full of it.
However, there is one simple truth that no boss will ever tell you, even though it's vital both to your relationship with your boss and to the progress of your career: "I am not your mentor."
According to job descriptions as they're written today, managers are expected to coach employees on how to improve performance. Indeed, that's why what used to be called "salary reviews" have been renamed "performance reviews."
Companies go to great bother to create the impression that they're mentoring employees, especially younger ones. Corporate mission statements often emphasize the point, as do statements like "we're all family here."
Because of all the lip service, many employees (again, mostly the younger ones) naively believe their boss is supposed to be their mentor and help them develop themselves and their career.
But here's the thing: Being a manager always entails--at least to some extent--convincing employees to willingly do things that aren't necessarily in the best interests of the employees or their careers.
For example, when a company is about to be acquired by a private equity group, it's in the best interest of the employees to immediately find jobs elsewhere, because the PE firms usually destroy companies (and careers) in order to extract money from them.
However, it's in the best interest of both the current owner and the future owner (and the managers who represent them) to keep talented individuals on board until such time as the PE firm finds it expedient to fire them.
That's an extreme example, but the same conflict of interest plays itself out in smaller ways all the time.
For example, it's usually not in an employee's best interest to take on menial projects that are "below my pay grade."
Early in my career, my new boss asked me to type up a memo for him. I refused, knowing that the moment I typed him a memo, my new job would be typist/writer. I had big ambitions, so I refused point blank. He wasn't pleased.
Even back then, I had no illusions that my boss was supposed to be mentoring me but I can easily imagine that if I'd been under that illusion, I might have typed the memo as a favor because that's the kind of thing a "mentee" would do.
My boss would have been much happier if I'd complied because then 1) he'd get his memo typed, and 2) he wouldn't have to hunt and peck in the future (we had no typists on staff). So it would have been in his best interest to have positioned himself as a mentor.
Now that you've got the basic concept, you might be wondering why no boss will explicitly admit that "I'm not your mentor." Simple. Either a boss actually believes she's supposed to be a mentor or she actually doesn't believe it.
If she does believe that she's supposed to be mentoring, she'll never say "I'm not your mentor" because from her perspective that would be a lie and there would be no advantage to her to tell that lie.
On the other hand, if she knows that "boss as mentor" is a sham, she won't say so because it's to her advantage as a manager to leave you thinking that she's got your best interests at heart, because then you'll more easily comply with career-damaging requests.
This does not mean that you can't ever learn from your manager. Quite the contrary. It does mean, however, that you must remain constantly aware that your best interests and those of your employers can frequently diverge.