I would be lying if I said that to be a man comes without real meaning.
Political correctness and gender roles aside, there are characteristics that separate the men from the boys.
The more you fall under the stereotypical example of a man, the more likely you are to receive female attention. Argue this point all you want, biological fact says otherwise. The ideal man is tall, fairly muscular (but not overly so), confident, handsome, intelligent, bold, commanding, and independent. I'm willing to bet that most of you only have a few of these characteristics but some men are fortunate enough to have all.
However, it could also be argued that being a man is more about attitudes and approaches rather than characteristics. For example, Men are expected to be humble and respectful. Things such as sportsmanship, fairness, persistence and admitting fault relate to a man's pride and confidence in themselves. But also that they are willing to extend this attitude to their fellow men, whether or not they possess it. Things like being a liar, cheater, abuser, or manipulator is a sign of a 'weaker' man who is unable to deal with and manage the reality around them without playing dirty.
As for conventional family roles, it is generally expected for the Man to be the provider in a marriage. Though that is starting to change with the increased appearance of dual-income earners. When it comes to raising children, Men are expected to be tough leader types for their sons and attentive, compassionate role models for their daughters. This is to ensure that the boys grow up strong and independent while the women grow up to expect a certain standard of men in their lives (they gain their independence from their own character or maternal influence).
These are the most important areas where being a man is important. Every other aspect of life is completely dependant on who they are as individuals.