It sounds like it will return the localized x, y and z position (boundaries) of that item in a house so that you are able to know how big it is =difference between min to max.
May only work inside the furniture edit mode and placed furniture, in a house.

Maybe this esoui forum helps too:
https://www.esoui.com/forums/showthread.php?p=35916

The best way to understand the functions often is to search them in the esoui vanilla lua code to see how ZOs uses it.

You can either find the source code by using a tool like Black Book Browser to extract the files yourself, or by looking at the esoui github

That being said, I just looked through the source files and I couldn't find it myself. However, I also searched for it in essential housing tool's code (a housing addon), and found an instance where it was being used. Line 4654 in housing.lua.

EHT uses it as a way to find the bounding box of the item. For example, if an item is 1 meter in X, 2 meters in Y, and 3 meters in Z, and is placed at (4,3,2), then the output of the API function will be:

minLocalX=4, minLocalY=3, minLocalZ=2, maxLocalX=5, maxLocalY=5, maxLocalZ=5

It can then be used to find the dimensions of the box, by doing X = maxX-minX and so on. In addition, EHT uses it to show a physical box in the world around where the item is.

In addition, EHT also multiplies each of the values by 100. No idea why, maybe its normally in cm instead of meters?

From what I can tell however, the function will only get the bounding box, so if an object is rotated 45 degrees, some parts of the bounding box will be empty of contents, as the bounding box represents the maximum space being used by the object.