if so, how does it work?

Yes, I've used LexisNexis (although I have much more experience with Westlaw, their main competitor). I'm not sure exactly what you're asking, but in their own words, it offers "legal, news, public records and business information."

Since I'm an attorney, I mostly use it for performing legal research. I guess you could say there are three main things I do with LexisNexis:

1) If I have the citation for a case, statute, law review article, etc., I can simply type in the citation and retrieve that document. Most of the time I access LexisNexis from the county law library, and so I usually ask LexisNexis to email me the document. Within a minute or so, it shows up in my inbox as a Word document.

2) If I'm researching an issue, I use it to find legal authority so I can form a professional opinion and/or build an argument to support my client's position. There are various ways to go about this.

3) LexisNexis allows you to "Shepardize" a case; they have an online version of Shepard's Citations. This is handy for three reasons:

• Shepard's will give you the prior and subsequent history, if any, of a case. Generally speaking, you don't want to cite in your brief a case that's been reversed on appeal or later overruled.
  
• It's useful as a research tool. Shepard's will give you a list of all cases that have cited the case you entered. If I've found a case that's relevant to the issue I'm researching, Shepard's can point me to other cases dealing with the same issue.
  
• Shepardizing a case the old-fashioned way takes forever. You've got to look it up in the bound book and multiple supplements. Furthermore, the tables in the print version of Shepard's are about as easy to read as the stock quotes in a newspaper.
  

If you have a LexisNexis account, you should be able to take advantage of free, live classes on how to use it. Also, I'm not sure about LexisNexis, but I know that Westlaw offers free telephone support.

Thanks, there's a job I might apply to that ask for knowledge of Lexisnexis