What does 'conversion rate' mean?

http://bit.do/dpMcG Secret promo page at Omniconvert.
http://www.doubleconversions.com A clip from the full Double Your Conversions interview with Sasha Gilberg where he teaches us the important elements of a website that need to be split tested in order to increase conversions. Watch the full interview: http://youtu.be/ne96cslHK10