I have looked it up in Oxford dictionary and it says it means to accomplish one's porpouse on. But I do not quite understand it. Here is an example of the phrase in a sentence from thedictionary that I cannot get: "At least I can still work my will on the minds of others." what does that mean?
It is not an ideal example because it is hard to imagine anyone sane uttering it. What it literally means is
At least I can still make the minds of others think what I want them to think
If, indeed, the speaker can control the thoughts (and therefore by implication the beliefs, emotions, and motives) of other human beings, that seems to be the maximum in human power, not the least of anything. But of course, it cannot be literally true; someone with great power of persuasion might say it as ironic hyperbole.
Let's try a more typical example.
The lascivious duke worked his will on the pretty young maidservant means that the duke sexually enjoyed the maidservant. (Maybe I have a future writing for Harlequin Romance.)