An objective is a measure of your satisfaction with possible outcomes. It might be net present value, lives saved, or EBITDA, or more generally, utility. Usually, the decision maker is trying to find decisions to maximize (or minimize) the objective.
Often, an objective combines multiple sub-objectives or attributes, which may be in conflict – such as energy costs, and environmental and health risks. Usually, when the objective is uncertain, decision analysts suggest maximizing the expected value, or more generally, expected utility, based on risk preference.