to bring something about by working at it: to produce a result, carry out a deed, or accomplish a task fully
This verb is built from the ordinary word for working plus a prefix that pushes the action all the way through to its finish. So it is never just "to work"; it is to work at something until it comes out as a finished result. English has to reach for different words depending on what is being brought about: a cause that produces an effect, a person who carries out a deed, or an effort that completes a task.
When the thing produced is a state or outcome in someone, the word names the whole chain from cause to effect: the law produces wrath, suffering produces endurance, godly sorrow produces repentance. When the thing brought about is a deed, the word means to carry it out or perform it, from shameful acts to the good a person cannot manage to do. And when the object is a work or task, it means to bring it to completion, or even to prepare someone for what comes next.
This is overwhelmingly Paul's word: nearly all its uses are in his letters, where he leans on it to trace how one thing works its full effect in another. That is why it shows up so often in his arguments about sin, suffering, and salvation, where the point is not merely that something happens but that it drives all the way through to a definite result.