By default a fairly non descriptive name is given to the item but I recommend you do not use it. Instead create a more descriptive name.
I thought I'd share the naming convention I use with AdSense that I've found to be very helpful especially now that AdSense has upgraded to the new AdSense interface.
My AdSense naming convention takes takes the form:
Where SiteID is a unique identifier that lets me know what site the Ad Unit, Link Unit, etc was created for. Instead of using the full site domain, I use some sort of abbreviation or acronym so it's only a few characters long. It doesn't really matter what you use as long as you're consistent.
For example, on this site I'd use the SiteID of HTNMMO for HowToNotMakeMoneyOnline.com. So whenever I see anything in my AdSense settings or AdSense Reports that starts with HTNMMO I know it's for this site.
SectionID is optional but useful on larger or more complex sites. I use it when a site has different sections such as a blog, articles, forum or different categories.
Placement is a short description I use to identify where I intend to place the item in my website. Examples can be PostBodyTop, RightSidebarTop, etc.
I try to be consistent across all my sites. The overall name is still unique because of the SiteID prefix.
TYPE identifies what type of item it is. AU for AdUnit, LU for Link Unit, CH for Channel, etc.
If I'm looking around AdSense and I see something called HTNMMO-Blog-RightSidebarTop-AU I quickly know what site the item belongs too and I know it's referring to the Ad Unit on the right sidebar at the top.
When I'm creating reports to analyze my results to help optimize my AdSense revenues I can quickly filter items. If I want to see all ad units on a particular blog I filter using the SiteId. If I want to see how well ad units that are placed in sidebars across all my sites I filter for the word Sidebar. If I'm looking to see how well my forums do with AdSense I filter for the word forum. You get the idea.
This one little AdSense tip has allowed me to get more with AdSense because the reports are much clearer.
What type of naming convention do you use with AdSense?