kv means rpm per volt applied.
Thus the 1100kv motor
does 1100rpm / Volt OFF LOAD!
3639: These 4 digit numbers generally mean diameter and length; i.e. 36mm diameter, 39mm length.
xS means the number of cells, of nominal voltage
3.7V for LiPos.
Thus 3S is a 3 cell battery
of nominal 11.1V.
25C is a theoretical measure of maximum short term current the battery
can deliver in terms of a multiple of it's nominal capacity in Amp hours.
Thus in this case 5.8 x 25A = 137.5A. But not for long!! and afterwards the battery
would most likely be wrecked and useless.🤔
So it's really only a marketing gimmick not to be taken very seriously.
Hope this unravels some of the mystery, cheers Doug 😎