It generally means his emotional attachment to his work. Does he like like it? Does he love it? Does he hate it? Does it satisfy him?
If you change "feel" to "think", the questions would be more factual in nature.
Student or Learner
What does the feel about mean?
e.g. how should he feel about his work?
Thank you for your quick reply. But if the question is talking about the person then, e.g. how do you feel about him or her?