LEVENE: You're sending Roma out. Fine. He's a good man. (1.1.3-4)
If a man is good at his job, he's a good man. This is a theme we keep coming back to in the play. A man's deeds and actions are irrelevant, and the only thing that makes him a man is his ability to make things happen in business.
LEVENE: Put a proven man out (1.1.15)
Okay, so Roma is good at his job and he's a good man, but he's not as much of a man as Levene because Levene has been doing it longer. Manhood gets tied into age here, and it makes for an interesting conflict. You have a guy on the tail end of his career watching a younger man rise up the ranks. Levene isn't willing to let go of the man he was though, and he wears his past like a badge of honor.
LEVENE: Where did you learn that? In school? (1.1.95)
Ouch—low blow. The world of Glengarry Glen Ross is a world where college boy is a big time insult. Levene never respects Williamson as a man because he didn't earn his manhood out on the streets, and instead just picked up some tricks from books and school. That's not what a man does—a man works.