"Kv" means revolutions-per-minute per volt.
So higher is faster per volt, but with the big disclaimer that you'll potentially be using a higher voltage battery with a lower Kv motor which may end up being (theoretically) faster overall.
E.G. Standard 2S 7.4 volt battery with a 2200Kv motor ends up being 7.4*2200 = 16,280 revolutions per minute (theoretically according to the manufacturer).
Whereas a 4S battery will have 14.8 volts, and might be used with a "slower" 1600Kv motor, however that ends up being 14.8 * 1600 = 23,680 revolutions per minute
Hence why "slower" lower Kv can sometimes be faster, which I suspect is what may have been confusing you in the first place. It's cos the inputs are different.