I would guess it means that the site has verified that the ad poster is who she claims to be.  From what I have read, there are just as many fakes on EROS as any other site, so do your research.

Swim

Since they started their new program, there have been ads placed with fake photos and still listed as verified. You can't trust EROS. They make their money through the ads and they have spent a great deal of time and effort over the last 5 years to make it more difficult for hobbyists to research what is posted on their site. They disabled the "right click" to make it difficult to use sites such as tineye (there are work arounds). They hid the URL's so we couldn't lump them to particular agencies or groups. They tightened up their process for reporting fake ads. They are friends with the dollar, and no one else.

That said, they are "attempting" to verify the photos but there is no guarantee that the provider from the ad is going to show up. It is still easy to have a "verified" ad and send another horse out the gate.  
Your best bet is to cross reference with TER. Using EROS alone is not wise. Always check the reviews and profiles here to lessen your risk.

I got the seal on my ad by sending them my photo ID, unedited copies of my photos, and a photo of myself holding a sign with the date/my name/"Eros Authenticated." So it's pretty thorough.

I am it it means your legit, but not the case...

Eros has had issues with this since they started fake girls with fake ads & photos.  No bueno.

here or on another review site, do not waste your time.

with a non cropped photo of herself to compare. Then, any and all photos put up must be compared to that one, before they can be 'verified.' They make you hold a sign up saying your provider name, date, and Eros or some crap, then compare that to all other photos you submit.