Some of the most common uses: It has been finished. - This is recent news. It has been finished for (+ period of time)... / ...since (+ point in time)... - This how long it has been since it was finished. It had been finished when X happened. -The first past action had been completed before the second one occurred. It had been finished by (point in time). -The action was completed before a point in the past.

I'm going to give you a somewhat theoretical explanation. The tense of "it has been" is called "present perfect". It really does talk about the present more than the past. "Has" is present tense and "been" is the past participle of "to be". The phrase "Tom has been" means Tom presently has an EXPERIENCE of being. If Tom is dead, you usually should not say "Tom has been". It wouldn't make sense because Tom can no longer have anything. You would say instead "Tom was." (Actually, you could say he has been, but you would be imagining his non-living presence). "It has been finished" means it has "being finished" (right now) as an experience. It is a statement about the present, not the past. It says that right now, "being finished" is a history, or a memory, or an experience that it possesses.