D: The enjoyment of use of something.

Or for a company, this translates to

D: The productivity gained through of use of something.

Alternatively

D: The quantity which the decision process is trying to maximize.

In economic theory a rational entity (a person or people running company) will estimate the utility of something, and this will be closely reflected in how much they are willing to give up to get it - eg how much they are willing to pay for it.

A decision process typically is trying to maximize something - profit for the company, the probability of winning a competition, the hours of leisure, the amount of alcohol consumed and so on. Utility is just the name given to the entity which is to be maximized. Sometimes an entity is trying to maximize many things which involve a trade-off (eg the amount of income, and the leisure time), and utility is the entity which describes the trade-off ratios.

See