Can't even remember what ftp stands for myself!
There's different levels: amateur, active, expert then pro (I think). Each level has 10 sub levels. Geoff posted up a table many pages ago which shows the breakdown of what watts are requires to break through to the next level.
FTP = Functional Threshold Power
By definition this is the maximum average power you can sustain for an hour, and is considered to be a good match for the power output at which you are on the threshold of producing more lactate than your body can deal with, your Lactate Threshold.
The FTP test on bkool actually measures the average power over 20 minutes, as an hour is a bit of a slog. You are supposed to apply a correction by taking 95% of the 20 minute figure to approximate the hour average, and hence 95% of your average power on the FTP test gives an approximation for you FTP, which should be close to your LT.
Your FTP is more often quoted in Watts per Kg, which is considered a more useful measure of ability, so you should divide the 95% figure by your weight in Kg.
The bkool fitness levels are an arbitrary division of FTP as 95% of 20 minute average power per Kg, broken down into four categories and 10 sub categories: Amateur 1-10, Active 1-10, Pro 1-10 and Elite 1-10.
If you do not do regular FTP tests your fitness level will be determined using the average power from any session over 30 minutes.
Geoff