Value:That which you act to gain and/or keep.
In the widest sense, a value is something that someone pursues. It can be pursued for any reason, even a bad reason. The term just refers to the fact that it is valued by that person, and doesn't evaluate whether the person should value it.
In Objectivist ethics, it is recognized that only some values are actually beneficial to a person. This evaluation of the merits of a value is sometimes referred to as "an objective value", meaning it satisfies the criteria for being a proper value.
Value is a central premise in ethics. Ethics is about how we make choices, and our choices are based on what ends we value. Ethics tries to determine what ends you should pursue (which values you should pick), and how you should pursue them.