campaign_difficulty_handicap_effects_tables - confused with levels

[Greq7]

I would like to know what those levels mean exactly if someone knows this. I understand that :
-1 easy
0 normal
1 hard
2 very hard
3 legendary

So what -2 and -3 mean exactly that table?

thanks for helping

[Greq7]

-2 is very hard and -3 is legendary for human but it was confusing to find because there is also a tick for human so it just dont make sense but at least I found my answers.

-1 hard 0 normal and 1 easy