what does gfe+ and gfe++ stand for?

There no set definitions for GFE+ and GFE++.  It seems that some agencies make up these acronyms to signal their providers' willingness to offer services such as BBBJ and/or Greek.  

On the other board, a hobbyist by the name of St. Bart posted a scale that defined what 100% GFE meant.  I thought that scale provided pretty good clarity about the services offered by providers.  However, like most topics on these boards, that scale is still mired in controversy.  

The best you can do is carefully read as many reviews as possible regarding the providers you are interested in and make your own judgement.  You can also use the back channel to gather info on providers.  But, unless you have the same likes and dislikes as the person you are contacting, you may not always get advices that fit your individual needs.