Got this from the common terms thread on this forum.
Abbreviations Commonly Used In Reference To Snakes And/Or Corn Snakes
1.2.0 = 1 male 2 female 0 sex unknown
1.1 = would then mean 1 male 1 female, if there are no unknowns then it is often left out
I had to ask the same question when I got here too lol.