This is said at Willy's funeral. Here is part of the talk over Willy's grave:
LINDA: I can’t understand it. At this time especially. First time in thirty-five years we were just about free and clear. He only needed a little salary. He was even finished with the dentist.
CHARLEY: No man only needs a little salary.
LINDA: I can’t understand it.
What Linda doesn't understand is that, for a man like Willy, a salary is not just about paying the bills. Some people work in order to live; Willy lives in order to work. Work, and the money it brings, is what defines him as a successful human being, gives him self-confidence, feeds his ego. The more money he earns, the more powerful he feels in relationship to others. And if he's just earning enough to get by, a "little salary," that's not enough at all; it's not the point.
Happy, the son who inherited Willy's preoccupation with the money-equals-success equation, put it this way earlier in the play:
BIFF: But look at your friend. Builds an estate and then hasn’t the peace of mind to live in it.
HAPPY: Yeah, but when he walks into the store the waves part in front of him. That’s fifty-two thousand dollars a year coming through the revolving door, and I got more in my pinky finger than he’s got in his head.
BIFF: Yeah, but you just said...
HAPPY: I gotta show some of those pompous, self-important executives over there that Hap Loman can make the grade.
No, for some, a salary is not for buying things; it's for feeling like you're a man and you've "made it."