It’s a link to a CFX which will allow you to generate CAPTCHA’s for your website. What’s a CAPTCHA you ask? It’s those cool images which have text and a crazy background which is readable by humans (well most of us anyhow) and hard (not impossible) for computers (ie spam bots) to read and decipher.
It’s primarily used in conjunction with a login script, or a sign-up script to prevent people from automating sign-up’s or generating a ton of false accounts etc.
Learn more about CAPTCHA here.